The first place I would recommend you start is with the official OOTP Manual, which you can access through the game (or even just find through a browser search). It won't capture all of the nuances and is sometimes a bit outdated but it is a great starting off point for understanding how the game works. I'm personally not a read the manual kind of guy but it is a place to look up specific topics when you are feeling lost.
I would also recommend you check out the various YouTube videos, particularly focusing at first on the tutorials. There are a number of them put out by OOTP Developments and in fact Alex Murray (AZAxel) is currently in the midst of releasing a series of shorter focused tutorial videos. You might also want to watch YouTube videos of OOTP'ers simply playing the game as you can learn just watching. Which ones will be most useful or enjoyable for you I couldn't guess, but I particularly enjoy those produced by pfholden and he also has put out several good tutorials on OOTP as well.
When I first started playing OOTP I read as much here, particularly in the general discussions subfolder and this new to the game subfolder, as possible just to glean information and get a bigger picture understanding of the game. I also found some very helpful user guides on the OOTP subreddit. There is a quite exhaustive one that is from 2017 I believe that might be slightly outdated but contains good information. You should be able to find that by entering key words OOTP user guide reddit or some variation on that in your browser's search engine.
One thing to keep in mind is that through these various sources you may actually see conflicting information and there will be individual biases being presented. Eventually you have to sort out what works for you or what you think is the best way to approach the game for yourself by doing and failing and doing again, etc.
My main piece of advice other than all of this is to start small, start simple, start with something you know, be okay with messing things up and needing to start again, consider failures as learning opportunities, etc. This is a deep and immersive and complex game and it offers great opportunities for enjoyment but also for frustration. The learning curve is steep, but certainly not unconquerable. The game is very flexible in terms of options and styles of play and I would recommend that at first you don't try to take on too much in terms of organizational tasks (maybe start just as manager or just as G.M. and delegate a great number of things, like minor league roster management and the like, to your staff/the AI).
Mostly, hang in there. If you are anything like me (no guarantee of that, of course
) you will find that this game offers you many, many years and thousands of hours of enjoyment ahead and over time things will begin to click and if anything you will be looking for new ways to challenge yourself in the game.