Well,
First you will need a CGI (Perl/php) to parse form data. Google will be your friend.
Next output form data to a file:
Perl Based code.
open(OUT,">formdata.txt");
print OUT "FNAME $FORMDATA[0]\tLNAME $FORMDATA[1]\tEMAIL $FORMDATA[2]\n";
print "Thanks for submitting our form.<p>";
close OUT;