function CheckF()
{
  var f = document.form1;
  if (f.firstname.value.length == 0)
  {
    alert("First name field cannot be empty.")
    f.firstname.focus()
    return false;
  }
  else
  {
     if (f.surname.value.length == 0)
     {
        alert("Last name field cannot be empty.")
        f.surname.focus()
        return false;
     }
     else
     {
        if (f.address.value.length == 0)
        {
          alert("Address field cannot be empty.")
          f.address.focus()
          return false;
        }
        else
        {
           if (f.suburb.value.length == 0)
           {
               alert("Suburb field cannot be empty.")
               f.suburb.focus()
               return false;
            }
            
                else
                {
                    if (f.email.value.length == 0)
                    {
                       alert("email field cannot be empty.")
                       f.email.focus()
                       return false;
                    }
                    else
                    {
                       if (f.username1.value.length == 0)
                       {
                          alert("Preferred User Name (1) field cannot be empty.")
                          f.username1.focus()
                          return false;
                       }
                       else
                       {
                           if (f.username2.value.length == 0)
                           {
                              alert("Preferred User Name (2) field cannot be empty.")
                              f.username2.focus()
                              return false;
                           }
                           else
                           {
                              if (f.password.value.length == 0)
                              {
                                 alert("Preferred Password field cannot be empty.")
                                 f.password.focus()
                                 return false;
                              }
                              
                                 else
                                 { 
                                    if(f.paymentmethod[0].checked)
                                    {
                                         if(f.chequenumber.value.length == 0)
                                         {
                                             alert("Cheque/Order no field cannot be empty.")
                                              f.chequenumber.focus()
                                              return false;
                                         }
                                         else
                                         {
                                             if(f.datesent.value.length == 0)
                                             {
                                                alert("Date sent field cannot be empty.")
                                                f.datesent.focus()
                                                return false;
                                             }
                                             else
                                             {
                                                f.submit()
                                             } 
                                         }                               
                                    }      
                                    if(f.paymentmethod[1].checked)
                                    {
                                         if(f.depositdate.value.length == 0)
                                         {
                                             alert("Deposit Date field cannot be empty.")
                                              f.depositdate.focus()
                                              return false;
                                         }
                                         else
                                         {
                                             if(f.bank.value.length == 0)
                                             {
                                                alert("Bank field cannot be empty.")
                                                f.bank.focus()
                                                return false;
                                             }
                                             else
                                             {
                                               if(f.branch.value.length == 0)
                                               {
                                                   alert("Branch field cannot be empty.")
                                                   f.branch.focus()
                                                   return false;
                                                }
                                                else
                                                {
                                                    f.submit()
                                                }
                                             }
                                         }
                                    }
                                    if(f.paymentmethod[2].checked)
                                    {
                                         if(f.cardholder.value.length == 0)
                                         {
                                             alert("Name of Card Holder field cannot be empty.")
                                              f.cardholder.focus()
                                              return false;
                                         }
                                         else
                                         {
                                             if(f.Cardnumber.value.length == 0)
                                             {
                                                alert("Card Number field cannot be empty.")
                                                f.Cardnumber.focus()
                                                return false;
                                             }
                                             else
                                             {
                                               if(f.expiry.value.length == 0)
                                               {
                                                   alert("Expiry Date field cannot be empty.")
                                                   f.expiry.focus()
                                                   return false;
                                                }
                                                else
                                                {
                                                    f.submit()
                                                }
                                             }
                                         }
                                    }

                                  }
                              } 
                          }
                      }
                   }
                }
            }
        }
     
  
}