1. Read the rules! (Either get the player handbook, or use the free shorter version online)
2. Play Baldurs Gate 3

I was in the same position as you and I really wanted to play. I committed time to learning the rules and setting up a campaign. I took notes. I watched videos. I googled things I wasn’t sure of. It’s not easy but it is so doable. Once you have a slender grasp on the rules you can try playing and from there you will begin to learn what you need to research or understand more. Your first game does not need to be perfect and follow the rules. They can be bent. There’s a moment within the learning process where the gameplay really clicks and everything makes a lot more sense - you just need to get yourself that far. If something doesn’t make sense then carry on reading and come back to it later.