im done!!! and with that I have a new problem!

As you can see its not the best but its my first ever model and i say it looked pretty good lol Even though he looks like a soft a cuddlily verison of The Hobbit Guys render lol . My problem is this how do i get my background to change from black to a nice color, to a nice blue color, and make my render look like this render;

the hobbit guys render

https://www.thehobbitguy.com/tutorial...ing/index.html

in that one i want my to be like that with the clay look and spotlight, or this would be very cool too;

https://www.3dm3.com/tutorials/maya/arch/index3.php

scroll down to the bottom to see his final renders.

I really like the blue clay look, i love it! I see so many good renders be like this.

I read somewhere that you need the GI_Joe mel thing, and i got that but i dont know how to use or where to put it.