Hey there! Welcome aboard.
For most DCS aircraft (except Flaming Cliffs 3 modules like the A-10A, F-15C, MiG-29, Su-27, Su-33) you can look here: https://forums.eagle.ru/showthread.php?t=135765
It's basically a step-by-step walkthrough that you can have either printed out, or on a tablet or on your phone, This should help you figuring out what to know and in what order. We all went through that "oh my god what do all these switches do?" phase at some point. Don't let that intimidate you. It's perfectly normal; it's a steep learning curve. The key here is to NOT be afraid to ask questions around here in the forums. Even if you think it's a dumb question, ask it!
My advice for you is to concentrate on setting up your controls first, then how to start the aircraft, than how to takeoff and land... and only once you've got that stuff figured out THEN you can start learning about weapons, countermeasures, radar and all that fun stuff.