Every page in CourseForum allows posting questions, and usually the questions would be related directly to a lecture or assignment, so can be posted on those pages. However, it doesn't hurt to have a general Q&A page available from right off the Home page.
As with other pages, you can monitor when people have added questions using the 'Recent Changes'. Encourage other students, teaching assistants, etc. to answer questions that come up, as well as answering some yourself. Place answers right after the question, by using 'Edit'.
If questions or answers become too involved, move them onto their own page (using 'New Page', then cut and paste from the Edit pages), leaving a link in the original Q&A page. That will allow in-depth discussion of particular topics.