Almost all Linux distributions fallow the standered that "Server" does not include any GUI software. GUI software takes a lot of RAM and CPU cycles for a server busy severing data. Desktop environments or DE's are the graphical component that you actually see and interface with. A DE runs on top of Xserver. Xserver is often started with the command "startx" however Fedora utilizes security conventions that forbid you from logging into a DE as root so you must execute the command as a normal user.
There are a verity of DE's avlible. LXDE being among the lightest and KDE being the richest in eyecandy. Gnome appears to be Fedora's Default. XFCE an option as well but I haven't used it in years since LXDE came out so I can't speak to it's use.
For LXDE
yum groupinstall lxde-desktop
Or for Gnome
yum groupinstall gnome-desktop
Research suggests that KDE is not as painless to install and doesn't lend well to group install on fedora 21 at prestent time. Doesn't sound like that would discourage you though.
Hope this information is helpful.