Now that you have a proper Power Supply Unit to energize your pc, you should be ready to add some pre-lit fans. Fans are good not only for cooling a souped up pc but can be used for  decoration. Some supplies you will need are the fans, and grills. (faceplates or grills are purchased separate from the fans themselves) You will also need a drill with a forstner bit to match the size of the hole you intend to cut, and a little common sense.

I started with Rosewill prelit 80mm fan X 2 and Rosewill prelit 120mm fan X 3. They come in assorted colors and only cost a few dollars a peice. I removed the side of my pc case and let my drill do the rest of the work. It is probably a good idea to borrow a friend when doing this part as I had a few problems with my pc case door sliding around and spinning as i was drilling my holes. As well, it may be a good idea to invest in some safety goggles as small shards of metal can fly up and hit the eyes.

For each fan I drilled 4 screwholes and one large center fan hole. See the picture below

TIPS

-make a pattern from regular paper with an outline of the fans screw widths and tape it to your pc case so you know where to drill.

-always make sure your pc is turned off and unplugged before opening the computer case.

-Make sure your fan is placed well!! It is a good idea to tape the fan to the inside of the case and attempt to close the case with the fan in position, this will ensure that other components do not already use that space.

After drilling the holes in your pc case It should look somewhat like the above picture. Although it is not absolutely necessary, it is recommended that you take a small metal file and relieve your new holes of excess metal protrusions. That is to say smooth out the rough edges. I have put pc's back together quickly just to use them and not bothered with the rough edges at all. What happens in this case is small dust bunnies attach themselves to the metal barbs and the case begins to look dirty rather quickly.

After drilling the hole installing the fan is easy. Screw the faceplate into the small screwholes and into the fan on the other side making sure your fan is setting so that it blows out of the computer.  With any  luck  you should end up with something that looks similar to the picture below.

In order for your fans to work they must be plugged into a power source.  There are 3 fairly easy ways in which you can do this. 

1.  Check your motherboard for extra fan slots.  (See picture)

2."Piggyback" Check the connection between another fan and the power supply and plug into the back of it, similar to adding another row of Christmas lights on a Christmas tree.

3. Find an extra power line coming off of your power supply.