How do I strap my shoulder to prevent it from being dislocated?

See an Ortho Doc to- Be treated properly as recurrence ( getting dislocations again and again) is rather high in young adults. You'll need physiotherapy to increase the strength in the muscles and you'll be taught the do's ; don'ts of protecting the shoulder. Strapping by itself might not be enough to prevent recurrence. So seeing an orthopod would be beneficial to you. Good luck.
Multiple braces. http://www.betterbraces.com/shoulder-braces/shoulder-and-clavicle-support?avad=55963_b62df623;affid=avant site above has examples. I am not endorsing that site or any of the brands, but it shows multiple braces that can be used to support your shoulder. Wrapping alone normally will not help as you need the increased rigidity of the brace. Pt can help by bracing stabilizers and is recommended.