2
1. You need to take the theme out of the compressed file, create a normal, readbale directory, then upload that to your themes directory.
2. Once you've done those things go to systems admin>>site preferences>> general settings and add the new theme to selctable themes.
3. Next go to systems admin>> blocks and add theme your site.
Go to HomePage and pick your theme to see if you like the way it looks. If you like things, undo steps 2 & 3.