The key to learning any tabletop roleplaying game is in three steps. You need to learn:
1. Book Layout
2. Basic Conflict
3. Character Creation
You can learn these in any order that feels right to you, but one way or another, you can’t play or run a tabletop RPG without knowing these things.
Layout is the easiest.
Look through the table of contents.
Look at the titles of chapters, make a note of where the character creation and basic rules chapters are.
Make a note of other cool looking stuff.
Basic Conflict is usually a much shorter thing to learn, since not many games use too many dice rolling processes. The two important things to make a note of are what dice the game uses, and how difficulty of rolls scales.
Knowing this gives you the tools you need to improvise a rulings, in the case you don’t remember where a certain system is in the book, or if you know the kind of system you want to use doesn’t exist in the rulebook for your game.
Character Creation is usually its own chapter in most games. Get some scratch paper and a pencil, read through that chapter, and make a character as you’re reading through it.
When you’ve done all of these, you’re more or less ready to run or play in a game. If you still feel a little nervous, make up a few practice scenarios and run through them with your made up character.
One such scenario you could go with is picking out an NPCs stat block, and running a mock fight between them and your character. Or you can take a look at the chart of difficulties, and see how many attempts it takes to get three successful rolls for a certain difficulty.
