The instructions are rather basic actually. You just need to know your basic traffic pattern sequencing and the rest is pretty self-explanatory. “Turn right heading 240” “Descend and maintain 3000” etc. If you get the “Please follow instructions” command but don’t know what you did wrong, I strongly suggest reading back through your ATC comm log where you can read all your instructions that were issued to you and see what you didn’t follow.
Nothing to be worried about. Just make sure you know basic terminology and you should be fine. You’ll get the hang of it, and soon you’ll be loving the Expert server!
Here’s a graphic I suggest memorizing: