Ingame documentation is scant, and if it's a "maintain" shouldn't it describe somewhere how to use this?
If you're level 6, you're outside the tutorial zone and into Millenium City proper.
One of the first missions you get is to go to the powerhouse (y'know that enormous, gear-shaped teleportation gate that's impossible to miss, where the trainers are so you can level up), and
watch several videos, one of which
explains the difference between Charges, Maintains, and Clicks. Hell, it even
demonstrates.
The documentation is
there, you either didn't read your mission objectives, or you outright ignored them so you could complain.