Youtube and this site are your friend on this one. There are so many variations on frames, flight controllers, motors escs. Then controllers massive choice not just on size and layout but the type of signal they transmit. Then you have video transmission, analogue or digital then on digital there are different manufacturers with different protocols.
Then once built you are going to have to learn Betaflight so you can program it all so they work together.
My first advise would be have a look at a controller that you would like, possibly go to a meet up and see shat others are using. Once you’ve bought that get on the simulator and get some hours in.