Hi Lester, and welcome to the forum! Hope you'll have fun with NESmaker.
I'd recommend going through the tutorials at https://www.thenew8bitheroes.com/learn to get the idea and feel for the software and how certain things work in NESmaker. Also, the first episode of the new series "The Twelve Days of NESmas" is all about the pixel editor, which I think will answer your question about sprite editing:
You will learn everything to know about NESmaker, how it works, how to set the elements and ho to make you first NES games. And stick to you see, don't deviate from them.
Then, you will be ready to start working on your own projects.