I have two blocks and one forum on the forum page. The two blocks are located below the forum and all three are in the center of the page. The forum and two blocks expand to the right but not to the left. How would I make the forum and two blocks expand to fit the entire screen?

That is controlled by your theme, which quite often assumes that there will be a left block area.

You can do this:
1. Open the theme.html of your theme in your favourite HTML editor
2. change this code:


to

3. Upload to the webserver
4. Enable "update module templates from themes/yourtheme folder" in system admin -> preferences -> general settings
5. See if the theme is as you want it
6. If yes, disable the "update module templates..." setting again. If no, go to item 1 and try again

Thanks