Ok, step-by-step if you have trouble with the forum.
SIGNING UP:
First, hit the register button on the banner near the top of the page. The button is on the right part of the banner.
Fill out the information needed.
Open your email, and hit the link in the conformation email sent to you.
Log in using your user name and password you used during the registration process.
POSTING
Click on the topic called "Ideas for Project"
That will take you to the forum page, there is currently one forum, also called "Ideas For Project". Click on that.
To post a message, click on the button near the top left called "Post Reply"
Write your message, and hit send.