How do I straighten a photo?

[Marmalade]

thanks for all the help
Picassa was easier, but now that I know what to do in photo shop it seems simple too.

[xxpinballxx]

this one will look odd after straightening.....you would need to rotate the image about 8 degrees or more counter clockwise. And seeing as how there isnt much matter there on the right side it will be narrow vertically compared to the way it is now and lose a lot of the frame. this is what it would be like once leveled. now you can see how cropping would lose some of the frame.