How do I even my vertebrae courtyard? It has a slight slope downwards towards the subsidise fence. ...

It has a slight slope downwards towards the subsidise fence. We want to put a pool up but nearby is no level ground.

If we put dirt down to swarm it, would it wash away even if we planted more grass? (We hold St. Augustine now, if that matter.)
Answers:    it will not wash away
if you put grass on it
attach soil but water it surrounded by to help compact it
the substance of the pool will also help

or you can basically cut the high side down to plane it out
Who ever installs your pool will know what to do, if it is an above ground pool the best thing to do would to use some garden bricks, and get a retaining wall to level out the nouns for your pool.