And my computer can run it so What tips you got for a bigginer such as I?

Which game did you get? Or did you get all of them? Are you an expert/average/beginner FPS player?

If you got all of them and want to play through the story in order go Clear Sky -> SoC -> CoP.
If you are after the "What STALKER has to offer" experience go SoC -> Clear Sky -> CoP.

SoC and CoP are quite good without mods, but Clear Sky really needs mods to get it to the level of the other two. If you are short on time you can skip Clear Sky entirely. I didn't think it did much for the series except for adding a story before SoC.

If you are an expert FPS player, choose the highest difficulty. For average/beginner I think start on the easiest until you finish the game at least once. Being an average FPS player, I found it difficult enough to reach the end on easiest, even after finishing the games a few times.

The only other tip I have is, sometimes the text says something is "in the cellar", but I always find them in the attic.