One year ago, I am a beginner too. When I first met Godot I also asked the same question.
Now I am still learning, but I already made some playable 2D small games. The following is my personal experience.
Using Godot Doc like look up in a dictionary.
This page is quite useful for me. It contains lots of video tutorials for Godot. And here is a beginner tutorial for 2D game. You can fine lots infomation in Godot Doc.
Start from clone a small simple game.
I mean " learning by imitation" is a simple way for starter.
If you are a beginner, you can try to clone "bricks", " space shooter", "flappy bird", "Mario", etc...
Youtube has lots vedio about how to clone those games in Godot, you can use keyword search like this.
Make first game in short limit time.
Don't try to make a big game in your first time, or you want to give up.
You can set a short time like 1 week to make your first 2D small game. When you finish first one then you can use longer time like 1 month to make your next game.
Make an easy version clone for games you like to play.
I mean "narrow down your goals" and make goals achievable.
For example, if you like Terraria, don't try to make a sandbox game at first! In first time you can make a simple platform that only has one small map with Player can move and jump only. And then try add more function for it, for example, coins, double jump, traps, enemies, NPCs, skills, save load functions, procedural map generation, etc...
Keep Try and Ask.
In my experience, "keep try" is really important.
Open your Godot engine, try to create your first scene, type your first code line. When you got "error message", try to print infomation about it, try to read those error messages, try search it in Godot Doc and internet, or try to ask it (Yes, you already did this, good job!).
Finally, this is the most important one. Don't give up!
I am not english native speaker, hope those words can help.