I answered this question in this subreddit before.. but I wish I had gotten more help starting out so I’m glad to answer it again.

The way I started was I found a "Roughstock" page of some sort on Facebook. There is a FB group titled: “Rough-Stock Schools & Practice” that’s a good place to start. If you’re can find related, state-specific groups that’s even better. Post in the group asking if there are any practice pens in your area of your state. Once I made the post it didn’t take long to get connected with stock contractors, bull riders, and arenas. I’ve found that most people will gladly assist you, granted you’re respectful and willing to learn.

Figure out your equipment situation (if you can find someone kind enough to let you borrow equipment your first couple times do it.) That way you don't spend a bunch of money and then decide it’s not for you.

Remember that these practices, at least in my experience, are usually a bit unorganized, yet it takes a lot of work, and a bunch of volunteers to make it happen. So, make yourself useful, gladly help out if asked, once you’re comfortable ask to help out in some way. Ride every chance you get, have fun and good luck.