About installing skins(quick please :))

[Crow]

You'll need to upload the image files to your host, most styles use there own folder for the images for that style.

I.E. - Style name is GreatStyle
in the zip file you might find a folder named greatstyle and inside this folder is the images for that style..

You'll want to upload this folder to your forums images dir.
It would look something like /forum/images/greatstyle
Hope that helps