On the Title Page for the Intro Physics Homework Forum, there is a button in the upper right hand corner of the page labeled "Post New Thread".
Press this button.
A blank Homework Template, consisting of three parts, will then be displayed.
Fill out the Homework Template and then hit the "Create Thread" button at the bottom of the page.
Your new thread should then be displayed on the Title Page. You may have to refresh the page view if it doesn't show right away.