You need to write some kind of program to run on the server; that accepts the data submitted in the form and outputs it to the text file. Such a program might only be a couple of lines long; but it needs to be there.
This program needs to be stored on your server in a publicly accessible folder with execute permissions ( I can't give any specific tips without knowing your server OS, and what lang you'd want to write the program in; but putting the program in the cgi-bin folder if you have one is usually a good way to give it execute permissions implicitly ). You then set the form's action attribute to the URL for your program.
For writing the program; if you use a scripting language like Perl, PHP ( or ASP if you have a windows server ); then you won't need any special tools other than a text editor and an FTP client.
Do some research into CGI ( the common gateway interface, which is a part of the means by which form submissions are sent to programs ), the languages PHP, Perl, and/or ASP, and file access in those languages.
Moderator
Featured Poster
Reputation Points: 522
Solved Threads: 64
Veteran Poster
Offline 1,091 posts
since Jul 2006