I would suggest that you learn the way most kids learn these days - work exclusively on balance first (I'd go so far as to remove the crankset and chain) and, when you've got that down, add pedaling to the mix. It's far easier than trying to do both at once.
Adjust the saddle so that you can place both feet on the ground (this will probably be a little lower than ideal when you're up and running) and start walking it around, getting a feel for the balance. Work on going a little faster, lifting both feet and gliding longer. It shouldn't take too long.
After you're good and comfortable with that, get the crankset/pedals/chain re-installed, find an appropriate gear and you'll be off to the races in short order.