I wonder if anybody could help me here.

I have a MYSQL database installed on my server and only supports php3 or cgi. all I want to do is user after registration would be able to login to the site immediately with their username and password. I believe it is kinda writing from form to database and read from database function.
My server does not support ASP. it has been 2 weeks now and nobody has given me a step by step instruction.

Please help me as it is very urgent