How do i change my Mac Os X theme??????

On windows see you can change it from blue, to olive green, to silver lol, well how do i change my MAC's theme, as in this:

(the things that are in a red box or on top of a red line in bold are the ones i want to change the color of)

http://img115.imageshack.us/img115/6641/



thanks 2 all who help!!!How do i change my Mac Os X theme??????
Sounds too difficult for me..I can tell you how to turn your computer off...that's about it..SorryHow do i change my Mac Os X theme??????
i have no clue sorry

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