Install Icon packages on Fedora 20

(It's assumed that GNOME Tweak Tool is already installed in the system.)

Icons are mostly packaged in tar.gz or .ZIP file. Let's get a couple of them from http://gnome-look.org/: Square-Beam 1.0 and The Circle 0.2 and install and use them. Click on their respective download links and get the Square-Beam_1_0.tar.gz and TheCircle.zip packages.

Now, navigate to the /home/username/Downloads folder (or to whichever directory you have downloaded them to):

# cd /home/username/Downloads

Extract Square-Beam_1_0.tar.gz to the /usr/share/icons directory:

# tar xzf Square-Beam_1_0.tar.gz -C /usr/share/icons

Unzip TheCircle.zip at the /usr/share/icons directory:

# unzip TheCircle.zip -d /usr/share/icons

Next, open GNOME Tweak Tool and select one of them, say, Square-Beam

Here's a glimpse of the Square-Beam 1.0 icon set:

And of The Circle 0.2: