and start riding on a day you're not working. Take a saturday to get acquainted, like a date. Start in a school playground or an empty parking lot. Just futz around. Remember how kids ride? do that. Go in circles, stop, start.. go as fast as you can.. stuff like that.
Get confident there and then expand your horizon.

Buying a junker bike probably means it will need work, so figure out which Local Bike Shop (LBS) is going to be the best one and start going there, buying stuff and getting to know them.
You need gloves and a helmet, for example.

Have fun, welcome to TE