You can contact your national or local association for more information on courses and competitions. Perhaps there is a Disc Golf course in your neighbourhood!
When there is no disc golf course available you can set up your own practice course easily. In a public park you’ll find more than enough things which can serve as targets: trees, lampposts, benches, dustbins. If need be you can use one target for a number of holes by setting up a number of tees with a mandatory route for the disc. For instance, the disc must pass a tree to the right-hand side. Start with small distances, where you can throw directly at the target. Later you can expand the distances and add “mandatory” trees or bushes. Eventually you can organise your own local disc golf event.