A picture is worth a thousand words, and Lord knows this would have helped this particular ID-10-T when he was trying to figure this out.
First things first. Fetch the tools you are going to need. If you haven't found out how to use the Add/Remove Software tool yet, bounce your mouse up into the left corner of your screen, and wait a second, then click the [APPLICATIONS] button (word) and wait a bit more. (Gnome Shell is a bit slow here. It has to build the datatbase, I think ... everytime. <..

..> ) If that didn't do it ... it's either a busted install, or you really need to go back and RTFM. If it did ... find the icon, start Add/Remove Software, type the indicated things into the search box when that finally settles down, (it needs to build a database of packages) and ...
Fetch the indicated packages, and if nothing goes wrong, the rest will get dragged in with dependencies. And, yes. You do need all of those bits listed in dependencies.
Once those are installed, log out, then back in.
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Now, using the file browser, create the
.themes folder. You can double check it was created by setting the preferences to show you hidden files. If you don't know how to do that, explore the options in the file browser (manager) menus. If that doesn't clear it up ... go to the fedora project documentation on the project site and ... RTFM.
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Now that the basic pieces are in place, download your selected theme from the repos, and skip to the part where you turn it on. If you're downloading a theme from some place like deviantart etc, put the downloaded file into the .themes folder, and unpack it there. (right click -- unpack here.)
Then start the gnome-tweak-tool.
Then select the active extensions
Then select the theme of choice.
A word or two about themes and choices is in order here. In F16/Gnome3/Gnome Shell, there are several elements which can be themed, and some which cannot ... yet. <..

..> Those elements can be treated seperately, or in a unit, depending on the theme itself. You, however, get to choose what parts of a "meta-theme" you wish to use on which elements. That means you may use Smooth-Inset for the shell theme, clearlooks for the window theme, and oxygen for the icon theme, etc. In short, explore a little, and don't be any too surprised if you get some random crashes out of it while you're at it. This is, after all, fedora. <..

..>
At this point, you may wish to restart the Gnome shell. To do so:
Press [alt]+[f2]
Type a single "r" into the dialog, and press [Enter]
Give it a minute to settle after the shell is reloaded, and explore your new theme.
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