|On a desktop computer replacing a case fan is very easy and a CPU fan is a little bit more involved. Open your case and watch while you start it (keep fingers out and avoid touching inside anyway unless unplugged AND you ground out any potential static charge you may have on yourself). If it is a case fan it usually is 4 screws or sometimes clips and one 3 pin plug. The CPU fan may require replacing the entire heat sink (depending on the design) and that requires you to remove the applied thermal compound and properly replace it. Depending your tech and skill level you may want to do this or take it to the shop, if you decide to do it, post back info on the fan/heat sink you see. If the CPU fan is simply bolted onto the heat sink then you may be able to replace it without removing the heat sink, but also look at the plug, many CPU fans use a 4 pin connector and you would be best looking for the same.|
Note, if this is under warranty still, contact the mfg. or where you purchased it instead of bothering yourself.
You have to be a little bit crazy to keep you from going insane.