This website helped me get started when I built mine 3 years ago. Amazingly I still have the bookmark
http://www.build-gaming-computers.com/
The first thing I did was pick a CPU and motherboard. Everything attaches to the motherboard, so make sure you get a good one with plenty of space and the correct type of slots for what you want. Then you just start picking the pieces, always double checking to make sure they are compatible and will fit. You don't need a soundcard. Graphics cards are huge and suck a lot of power, plan accordingly. Make sure to keep it cool in there, mine came with a big ass fan on one side of the case, so it's always cool for me.
Edit: also beware of static electricity. Don't build it in your room or any room with carpet, and get one of those silly looking wristbands. Don't risk your expensive parts
http://www.build-gaming-computers.com/
The first thing I did was pick a CPU and motherboard. Everything attaches to the motherboard, so make sure you get a good one with plenty of space and the correct type of slots for what you want. Then you just start picking the pieces, always double checking to make sure they are compatible and will fit. You don't need a soundcard. Graphics cards are huge and suck a lot of power, plan accordingly. Make sure to keep it cool in there, mine came with a big ass fan on one side of the case, so it's always cool for me.
Edit: also beware of static electricity. Don't build it in your room or any room with carpet, and get one of those silly looking wristbands. Don't risk your expensive parts