You can find the usual proxy settings for fedora in the network settings. Which is pretty straight forward. But this will not be applied to the yum installations that you do from the terminal. So for that you need to do a small addition in the yum.conffile that is present in the etcfolder.

Step 1: Head on to the etc folder and openyum.conf  using the vi editor. You can use the following command but before that.

Become the root user first by typing
su –
in the terminal and entering the password required.

Now type
vi /etc/yum.conf

This will open the yum.conf file in the vi editor.

Step 2:There will be many parameters already specified for about 5-7 lines. To this add another one

proxy=your_proxy_server:port_number

Example:proxy=http://proxy.abc.net:8080

This should do the trick

You can also add username and password if you are required to do so by specifying
proxy_username=johnsmith
proxy_password=smithjohn