Zoombrowser help

I'm just learning how to PP in Zoombrowser and can't find the answer in HELP. Can someone give me a few definitions and uses for the following: sharpen versus unsharp mask, radius and threshold? I'm using these in my PP but need more info on them. I'm doing a good job using this PP method but don't understand the particulars. Thanks

OC... You can't PP in Zoombrowser that I'm aware of, so I'm assuming this was an entry error. If not it might explain why you can't find anything to help in "Help" ! Do you have Photoshop Elements or Photoshop Creative Suite - which editing software are you using?

Zoombrowser does have a limited set of editing capabilities! Its Help sucks, that's all!

I don't know if Zoombrowser has a different use for each term, but...
'Radius' : the number of pixels to adjust around each edge, and values from 0.5 to 2.0 are generally good.
'Threshold': I assume is same as 'Clipping' or the difference adjacent pixels need to have before an 'edge' is sharpened
'Amount': I auume is same as 'Strength', or how intense of enhancement

The editing software I am using is the zoombrowser that was supplied with my XTi. The editing is quite simple. Sharpness, contrast and color correction is about all that is supplied. I don't have any other software for editing, such as Photoshop, etc. I wanted to learn this first phase of editing before I bought other editing software. I havent shot RAW yet but am anxious to try it. I just would like to learn this basic editing first. Any suggestions?