posttohost https posting

I am trying to use PHP to post values to a secure web site (https) but
can't get a response. I thought I should be able to just change to port
443 and talk with it like I can any other. Someone suggested CURL, which
allowed me to download the secure page but no provision for interativity.

I will have a username and password to pass to an initial page then
options to select there before I can actually get to the page I want to
fill out.

Any suggestions would be appreciated.

Thank you.

David Perry