Couple pointers on doing manuals. When you go into the trick, you wanna find your optimal balance point on your rear wheel. The front end of the bike should sit pretty level, you don't want to go in too crazy. You're going to use your arms and your elbows along with your knees to kinda pump and maintain that balance point. If you ride breaks you can also rely on those to help you maintain safety, where looping out where in which one should be going too far backwards, you can kinda tap the breaks to help bring the front end back around.
Other than that you wanna make sure upon exiting the manual you either wanna let the front wheel come down on it's own or kinda hop out of the manual. It's also a great way to link tricks if you're coming out of one trick you can land in a manual, go into something else. That's pretty much how to do a manual.