I’m guessing you’re asking how I manipulate backgrounds to make them have more depth?
Well, it’s fairly simple:

Basically, you wanna put in your key background first. Let’s say we’re doing a scene of a Rouxian camp out in the frozen northern tundra. In this instance, i might use the Arctic Plains background, preferably 2 as that one works real good. Then i want to add in a ‘Farground’, this is the background’s background. So i might use one of cliffs or moutains. I’ll probably use the ‘Stone Archway’ Background before putting the Utopia Wastes background behind that. Finnaly, I’d change the colour of the sky, add some fluffy clouds and big beaming sun.

Okay, so now we’re lookin’ pretty cool but the ground’s still pretty barren. I want this scene to look visually pleasing and in depth so I’ll add a Foreground, the mini-background at the front of everything. For this, i might use some rocks and my ‘Snow Platform’ fig and then blur them to 15/20%.

Next, the midground, the area characters do their thing. While you’ve been adding in backgrounds and foregrounds and the such, you need to make sure you don’t clutter up this area! In the midground we’ll slap in some Rouxians and their gear, maybe a HoverTank, maybe some crates or Fuel Tanks, heck maybe even a turret.

And BOOM! You’ve got a diverse Background!