Okay gcc. You have to understand Linux first. On Windows, you got one user, one administrator. One simple account who can do everything.
On Linux, you basically start with TWO accounts (for security reasons). One user, this is what you get by default. And, the "admin", the root.
On Ubuntu, they disabled the "admin". However, you can enable it if you use some command.
If you want to switch to the admin account (so you can mess around with that /usr/share), type:
sudo su .... Theeere you go, you became root, hell yeah.
HOWEVER, and this is IMPORTANT: You do NOT need that folder. Simply, open your file browser, in your home folder. Press
CTRL+H. Now, you see a LOTS of folders. Create a new one with the name of
.themes (note the "."). After this, copy the icon folder there. Check your icon settings (Appereance, Edit, icons) and its there. ! That's all.
Also: I don't want to be rude, and seriously, this is just an advice. You should search with Google at times like this. Just type in the crucial words like:
how to install icon theme ubuntu. You'll find a solution. It's faster, better, easier. Of course, I don't mind if you ask here, obviously not. But you'll need to help yourself out sometimes if you want to use a linux, and this is the very first step to get used to "Googleing".