I never made a cover for Season 9, but here is a guide on how I made the covers:

A. load up MLP Logo and make it square with the canvas tool. (5252 by 5250)
B. use Generation B font to make number in top right corner. (1500 px tall)
C. use drop shadow to add drop shadow to number x20 y20 16shade 40% opacity.
D. import pony vector and place in bottom left. (for later ones, leave the first pony layer (Twi) and compare to it to make sure each pony is the correct size)
E. use the picker tool to pick a color from the pony in that season's cover.
F. use the fill tool to fill the background that color. (took several attempts to find a color I liked)