1. read and watch everything you can about upwork / freelancing / etc
2. make a good profile (fill in all sections)
3. search for jobs that fit your skill set and submit proposals
4. keep learning, no matter what happens.
5. as you get clients, naturally, you build a history.
6. do all you can to keep clients 1000% happy and build your reputation.
I strongly recommend you check out the Upwork Academy in between submitted proposals. Regularly keeping up with Upwork Community's guidelines, especially via walking through the lessons in Upwork Academy will give you the in's and out's of landing your gigs and so much more. Keep submitting those proposals and touching up your cover letters. Best of luck landing your first gig!