Basic wrench question

Hello,
I have a pretty basic (I assume) question regarding adjusting my rear derailleur. I can’t shift into my biggest or my smallest gear in my rear cassette. The chain also skips sometimes over a few of the cogs. I know that there are 2 screws that adjust the traveling distnace of the derailleur. I don’t really want to bring my bike into the bike shop to have this adjusted. Is this simple enought that I can do it myself?

Any help is greatly appreciated.

Some reading for you:
http://sheldonbrown.com/derailer-adjustment.html

http://www.parktool.com/repair/readhowto.asp?id=64
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