My turn. :wink: An mtb is probably the best thing for any grown person to learn on. Here's my list of suggestions.
1. wear a helmet and gloves, for goodness sake, you've got palsy. :!:
2. find a somewhat open flat spot like an empty parking lot or open basketball court, with no traffic, so you are not restricted to one direction.
3. before mounting, rotate the crank with your foot while shifting to the large sprocket on the rear, and the middle sprocket in front. This will be fairly easy to pedal, and fast enough to get moving enough for easy balancing.
4. straddling the bike, rest the palm of your hand on top of the handlebar, with your thumb on top, as opposed to gripping it like a bat, with your fingers resting on the brake levers. You can easily switch when necessary, once you get riding.
5. on the side with which you would normally step first, rotate the pedal about 3/4 of the way up, towards the front.
6. stand on that pedal and as the bike starts to roll, lift your other foot to the other, and your butt to the seat. if you sit straight and keep the wheel pointed ahead of you, you should go, but unlike a trike, you have to keep moving to stay up. If you feel like you're going to fall, turn a lttle in that direction and you'll probably stay up.
7. if you manage to pedal a few turns without losing it, squeeze the brakes and as the bike stops, lean slightly and put your foot down on one side.
8. do it again a couple of times, once you can start and stop, the rest is a breeze. God bless and good luck. :wink: