Where do I go with the background?

I'm like, very unskilled in backgrounds, probably done three ever.. but I want to finish this more before I do shading

I can't find out how to do perspective lines for what I want. I only know how to move a horizon line up and down and move the point, and i can do two point perspective somewhat but never used it for a bg. I don't want the background to look so dramatically dynamic, but otherwise I don't know how to draw a background in a way that would look 3d, or where to place anything, without some sort of guide that I don't have.

I also want it to be probably just a casual grassy place with a bit of fence in the back, other details like flowers, rocks and whatever fantasy stuff I can think of. it is MLP lol🐴