I recently downloaded the UR4 and I would like to create a Super Mario sunshine like prototype what is the best way to start off. Please remember I’m new to so be gentle with me
Welcome!
Take a look at the basic video tutorials from epic games -> https://www.youtube/user/UnrealDevelopmentKit/playlists Especially the blueprint tutorials, because you will need blueprints for your project.
After that start a project with the 3rd person bp template and directly jump right into the fun -> create the character + animations, create all needed meshes,… 
Some useful links:
https://docs.unrealengine/latest/INT/
https://wiki.unrealengine/Main_Page
Note that all assets must be made from scratch if you are making a fanmade mario game. Someone recreated the first level of Mario 64 in Unity and got a C&D because he used some assets from existing Mario games.