You can upgrade Firefox by selecting help > check for updates. No need to uninstall Firefox 3.6.

Thanks, it worked. There is one other question you might be able to answer. I had a chat with the Firefox agent who knew less then I did about Firefox. It was as though we were talking about 2 different browsers. Anyway, once I opened Firefox 4, I wanted to group the 10 saved tabs that I use. I move the "Tab Groups" icon to the top menu and when I clicked on it, it opened another screen with the same page I was viewing. I could find no means to bring all 10 of the saved tabs to view on a single page. Any suggestions?