Hi Bob, welcome to the forum!
A few basic things come to mind:
1 Trikes don't lean in turns. You steer them, push the outside bar & pull the inside one. Think ATV or snowmobile. More work for your upper body but not that big a deal.
2 The rear end is wider than a bike. Need to allow for this around gas pumps, ect.
3 Trike will ride a little rougher on poorer roads. You now have 3 wheel tracks instead only one on a bike. One of the wheels will likely hit the rough spot.
4 Since you don't lean in curves, you will feel like you will slide sideways off the seat. You learn to brace your legs against the side pull. Push down on the outside floor board with your feet.
5 DO NOT put you feet down at stops, you might run up on your foot.
Trikes ride different from bikes but they are still a blast to ride. Some folks get used to them after a few miles, others may take several hundred miles. Just takes time in the saddle and ride at YOUR own pace until you get comfortable with it.
Best of luck to you!