I would not generally advise people to install their own parts, but with places charging 20+ dollars I am almost obligated to tell how to do it by yourself.
Before you do anything when installing something into a computer you have to make sure that you are not wearing anything that can cause you to build up static electricity since that can fry part. The casing on most computers are made to prevent static shocks so as long as you first touch the inside of the case before any parts you should be safe. Also in any stock computer every thing that is currently plugged into something will not end up unplugged (never leave an unplugged plug unplugged).
First I will start with something any person should be able to do themselves, RAM. You will be putting this on the motherboard and there will already be similar parts plugged in that looks like the RAM you have bought. The main problem with RAM is compatibility, if you do not have the RAM made for your motherboard it will not work. You can generally figure this out by looking up your computer at the manufacturing site.Following is a picture showing what the slot where the RAM goes looks like
For now this will be the end of my update and if you have any request just put it in a comment and I will help if i can.