I would like to touch up some pictures. I am really unfamiliar with it, but mainly for editing. What can you do with it? Is there a program where I can place logos on photos? or I can make things sharper? or more contrast in pictures? I use iphoto right now but the options are limited
Photoshop is a very advanced tool. Really what can't you do with it.
If this very basic form of editing is what you're after I suggest looking at GIMP first. It's a free opensource competitor. Also very advanced but missing only some of the finesse and features that very advanced editors would like to have.
It's also 100% cheaper than photoshop, and works as an excellent stop gap until you know how to properly and accurately answer the question icassell posted.
Paint Shop Pro X2 has more photoshop tools in it, than the Elements program at a price of $59 currently.
Viveza by Nik Software is more expensive at $250 but much faster to use than Photoshop in selective postprocessing since masking and layers are not required. Many pros use it for its speed. It is also extremely easy to learn and use.
In photoshop elements 6 you can add logos, make a logo, set it to be a brush so when you want your logo you select the brush and you can 'brush' on your logo, boarders are easy, sharpening, noise reduction, colour adjustment etc are all in it too