[Darthtanion]

Fans either snap into place within a case or are held in with simple metal screws. From there it is a simple matter to make sure it has power.

Of course, even though the installation of a fan is easy, you will also need to consider things like "does my case have fan mounts already in place" or if not then "how do I want to modify my case to accommodate the new fan(s)". Cooling is a straightforward concept but the fans need to be installed in the right place for you to maximize the cooling potential they offer.

As a rule you want cool air coming in from low front part of the enclosure and exhausting toward the upper rear areas. This allows heat's natural rising to get the hotter air to the exhaust fans and out of your system. You will also need to consider cable clutter and airflow. If you start boring holes in the side of the case without thought to the airflow that is already present, odds are good you will hinder the flow pattern and cause areas of turbulence... not good for overall cooling.

I can't help out much more without knowing what type of case you have or what cooling you already have in place, but the general rules noted above are good and offer solid cooling for a majority of the enclosures being used.