I know that you will laugh about this one, but:
How can I properly start with an F1 car on a race?

Sorry for the stupid question, but I'm a beginner, and I want to learn the proper, fast way. I have a wheel ofc.
Remember, none of you were born knowing how to drive fast in this game, so please, don't judge me. I want to learn.

Sorry, if I messed something up in my message; english is not my native language.

Not sure what you're asking, but if you're talking about the game then this is the wrong forum section.

You start literally by pressing the accelerator. The BF1 in this game has a paddle-shift transmission with automatic clutch. If you want to start the engine after turning it off, that's not possible. You have to reset the car in that case. If you're asking how not to spin out, well make sure you have TC (traction control) on and practice launches, preferably with something that isn't the fastest car in the game.

Practice starts with FBM first, try both full throttle and more subtle starts.
Do this with FOX & FO8 as well; try to get the feeling for single seaters with more power.
Then launching the BF1 with or without Traction Control will become easier for you. You can do it!