Changing default laptop keyboard shortcuts

I have a dell studio 1555 laptop. As you may know it has some default keyboard shortcuts at F1-5 and F7-12. Although I find them useful, I no longer know how to use these keys for things like refreshing a web page (F5) or closing a window (alt+F4). Not the most pressing issue, maybe, but I still find it quite annoying, if anyone has any suggestions or I'm missing something, advice would be very appreciated. Thanks