So the actual building would be to watch those YouTubes and what's next is part selection.
I'd start with builds from https://www.reddit.com/r/PCMasterRace/wiki/builds
If you feel you want to go into the beyond reason builds like trying to run a 4K gaming rig then I have a video for you.
i need some help and info on how to build a gamer pc on budget so im a noob to gamer pcs but have some computer experience so any help would be greatly appreciated
Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic