column sizes

Hello folks ,can someone please tell me how to make the topics and message columns the same size as my hompage so everything is displayed without having to scroll the page to the right to see everything, I have spent days trying to figure it out.

Ill try to make it more clear what my problem is. My homepage is a perfect size but when you click on a post its way to big for the screen, my members have also asked me to do something with it, its so frustrating , if only all the pages were in proportion like the main page.
Any help please its doing my head in lol