First PC : Help me finish it please

Brand of the GPU doesnt really matter - there is a difference in amount of FPS you do recieve from a slightly more expensive GPU as well as some cooling benefits (but this is negligible).

For the MB, RAM and PSU it will depend on what motherboard you decide to go with as well as any additional parts on your build as it will need more power.

I do recommend getting a very good PSU as your entire build does depend on it - Just ensure that whatever PSU you do end up deciding on is atleast gold rated and has an overall output of 200W above your max usage. 

feel free to check this tier list to get an idea regarding PSU's - PSU Tier List

MB is really upto you, RAM ideally I would try to pick up 32gb DDR5 (prices are really high but 16gb is a pain)

Hope this helps 😃