Dust will definitely cause problems in your computer and it should be cleaned our regularly.
#1. Always unplug the power cable before opening your computer. Make sure that you touch something metal on your case before anything else so if you have any static electricity, you discharge it safely on the case metal instead of on your expensive electronics.
Get some compressed air and blow out the dust. Be careful not to inhale the dust because it’s not good for you at all.
If you want to clean your fan particularly, you can use a q tip with a little alcohol.
Pulling the cpu fan off your processor and cleaning it manually would be a good option if you are comfortable with that process. If you’ve never done that before, I might not recommend that first.