I have great ideas for games (currently 5 ideas) but I have no idea how to use Unreal engine 4 at all, is there anyone who could help by pointing me to a helpful video or teaching me?
In the top bar. Learn -> Video Tutorials.
Hey Naleor01!
In Epic Launcher you can find Learn tab and it has a comprehensive list of guides, depending on your background - programmer, artist or just new to UE4. I recommend to check it out!
Welcome to the community @anonymous_user_304d49cc ; 
Start with the basics, and work your way up. Don’t be afraid to ask questions here on the forums, we don’t bite. Perhaps discuss some of your ideas your forum-goers and they can help set you on the right track with some things you might want to look into learning as a priority.
There are a number of excellent tutorials on Youtube on a number of specific game functions. Use the search terms “Unreal Engine 4 tutorial” to get a quite extensive list.
A number of topics have been covered in depth and a great deal of practical information can be found in threads here on the forum.
I want to try to make an open world game similar to something like fallout with levels, quests, and NPCs, but also like ARK survival evolved where you can create items, built structures and generally do whatever you want, is it even possible on UE4?
I’m new to everything
but thanks
Short answer: For a given quantity of possible, yes.
Long answer: The amount of work involved would take a single experienced developer years.
My advice would be to get started, learn the engine, experiment, hone your skills, then set a goal.
Youtube has tons of tutorials mate, get cracking.