First of all let me start by saying welcome to the forums! 
Congratulations on starting a new story.
I would say read as much helpful threads on the forums as possible. Check out this one, it’s probably my personal favourite. 
"List" of Helpful Threads
Also don’t hesitate to ask questions if you need help with anything, there’s a lot of people here who would be more than willing to help you, experienced authors, artists, background and overlay makers, you name it! The forums is a helpful environment and it also helps when you make genuine friendships with people who can also help you and vice versa.
Last but not least, just try your best, accept any constructive criticism and use to it to your advantage, constantly work on improving your story for yourself and your future readers.
Good luck with everything!