Put the Dunce Cap On

I upgraded the device driver for my video card (all by myself, with no tutor - aren't you proud of me?). Now when I open a site the window is set to small and I have to enlarge it (forgive my lack of the correct nomenclature) and can't remember how to set it so it opens "full screen." I remembered that this was covered on a recent thread here, but couldn't find it. Anybody got the quick fix? Thanks so much