Uploading Backgrounds and Objects

Okay i have a question here guys. I am new to Unreal Engine 4, so i don’t really know how things work yet. But i have a question

Lets say i want to make a side scroll game. 2D and all. Is it possible for me to upload my art work and use it as a back ground or even use it as model? I want to have as a background a sky. Can i draw this on a software and then upload it as a background? If so how?
I m having in mind the whole thing but im not quiet sure how Unreal Engine 4 works.