Don't know how to use Adobe Illustrator but...

So i have no clue on how to use adobe illustrator, i only know photoshop. not a lot is the same and it is very hard to me. it took me a year to finally figure out photoshop and illustrator is so much harder, i need help. no clue how to do anything, i set my pic to be 1920 x 1080 and i drew past the black outlined border but when i saved it, it was still in the pic like WHATTTTTTTTTTTTTTTTTTTTTTTT? btw, i know the drawing is very kidish, it wasa little cartoony drawing just to try out program.