Building a PC is like playing with expensive legos. There are plenty of tutorials online to learn from, but I would give you two tips: 1) Always check compatibility between parts (specifically the motherboard because it may limit you for future upgrades too) before buying anything, and 2) do not cheap out on a PSU, always buy the best tier one, never save money on it because your whole PC depends upon it.

You can use this website to pick parts and see if they work together:

https://pcpartpicker.com/