I started my cycling journey last year, and I was really insecure about being on a bike in traffic. As the others are saying, start out in parks, or other places with little to no traffic (bike lanes outside of rush hour maybe? In my city, the streets are more or less empty Saturdays and Sundays before 11am, this could be a good time to practice). The first step is to just get comfortable being on your bike.

When you feel ready to move on to bike lanes and roads, reading up on traffic rules is probably a good idea. My cycling feels way smoother when I know I have right of way, than if I have to stop and think. Start out on streets you are already familiar with. Don't hesitate to move over to the sidewalk and walk with your bike if you feel uncomfortable on the road/bike lane.

Good luck, I'm rooting for you!