A typical POST request to a CGI looks like this:
POST /cgi-bin/booksearch.pl HTTP/1.0
Referer: http://www.macfaq.com/sampleform.html
User-Agent: Mozilla/3.01 (Macintosh; I; PPC)
Content-length: 60
Content-type: text/x-www-form-urlencoded
Host: utopia.poly.edu:56435
username=Sadie%2C+Julie&realname=Women+Composers