Both, the .asp file extension and the syntax of your code seem to indicate that aspmailer.asp is written in Visual Basic. The name of this site is Perlmonks, because we focus on Perlon this site, a programming language different from Visual Basic.

I'm not sure where I'd turn if I had any problems with Visual Basic, since it has been years since I last wrote a non-trivial piece of Visual Basic.

Guessing from what you've given already, you might want to extend the Function SendMail like the following:

' Rename Field1 etc. to appropriate names
Function SendMail(From,Rcpt,Subject,Body,Field1,Field2,Field3)
Trim(From)
Trim(Rcpt)
Trim(Field1)
' and so on - Trim removes trailing and leading blanks from the field

If Len(From) < 1 Then  
ReportError strError & "<br>No email address entered"
End If

If Len(Field1) < 1 Then  
ReportError strError & "<br>No Field1 entered"
End If

' and so on
[download]

Most likely, you will also need to change all locations where SendMail is called to supply the new fields you've added.

Possibly, you should visit a programming class, to learn about programming in general and Visual Basic in specific.