session_start() sends a unique session id that you may relate to data in the form of a cookie to the user. sessions ids are all handled automatically with php core methods.
Why you are receiving the error is because you are attempting to send that session id (as a cookie) to the user after part of the HTML has already started. Due to the HTTP/1.1 request, and how it works, is it must receive cookies before any data is sent.
try this:
if (!session_id()) {
start_session;
}
Put it in a place at the top of the file. And good luck with wp-e-commerce. It took me a ton of work to get it working (even with the paid-for gold edition).
