I had so many issues with uploading themes. I too feel that install info is very grainy with install details left out.
Here is what I did that installs themes. I learned this from many days of fustration.
Let's use the 'fibubice' theme as an example.
Step by step instruction to install themes
Step 1.
You need a really good FTP program. I use WS_FTP It's a trial free version. It can be downloaded at
www.downloads.com
Step 2.
Unzip the file
Step 3.
Find this file. It will have the name of the theme. For instance, I am using "fibubice" as my theme for the site. So I will need to go find the "fibuice" in my documents. Which is where I usually put things.
Step 4.
Don't worry about the other files that come unzipped. You only want this one file, period. It is a good idea to read the license. The install info the themes come with leaves much to be desired. So don't worry. Help is on the way. Just follow the next steps.
Step 5.
Have this 'fibubice' ready. By that I mean be ready to upload. I like to drag it to an empty space(in documents are) all by itself. So it will be easy to find and upload. It just works for me.
Step 6.
Open the WS_FTP program. Log-in to your account at your server with WS_FTP.
Step 7.
When you are at the server. Follow this path (in the WS_FTP). You will be doing some clicking:
*public
*nuke--or whatever you named your site--I named mine nuke when I installed my site.
*themes
Then stop there. No more clicking
Step 8.
Now drag and drop the 'fibubice' file to an empty space in themes area (ws_ftp).
Step 9.
WS_FTP will make a sound when it's done uploading. It usually doesn't take long.
Step 10.
I like to close the WS_FTP program when it's done uploading. (I might drag and drop something else, who knows with my luck)
Step 11.
Now go to your regular account at your site, you don't want to do anything with your admin account just yet.
Step 12.
When you are at "Your Account" click on the themes icon.
Step 13.
From the choices of themes click on 'fibubice".
----Note---Going to "Your Account" to click on the newly installed theme will give you the chance to see if you like the theme or if there are any problems.
Step 14.
If you like what you see and there is no problems, then go into your Admin Account and click on Preferences and choose 'fibubice' (or the theme you just installed).
I hope this helps. I will write a another tutorial for installing modules as soon as I figure that one out. I will be studying on how to do that today. It's today's project.
I learned how to install blocks recently. So, I am on a roll. I don't mind sharing info.