220 cc's ( or ML ) of Fluid, and there's a coupla choices.
There's a level screw in the side, you can just pull it and fill till it starts to dribble.
Supposedly Dexron ATF is better, but I do not care for it - I use straight motor oil.
As for the "Whine" in first gear ?
Tomos mopeds simply make that noise, it's neither a fluid problem nor a worn gear, they make it brand new, and they make it thousands of miles later - mine still makes it at 21,000-someodd miles.
Any more hassles with it, just ask...