Though it may be intimidating at this stage, if you've watched some real play videos or listened to some real play podcasts and think you have a decent grasp of D&D rules or whatever RPG suits you, you could try GMing a game. I've found that's a great way to meet folks on Roll20 and find players similar in tastes to you. Many GMs are hungry to be a player, so you could find that if you GM just a one shot or brief campaign that could open doors for you and one of your players may invite you to their game. Also, if you apply for a game, be sure to read the instructions carefully and follow them. With so many players wanting to get into a game, GMs can be very selective, so don't disqualify yourself by not following directions. Try to find a game that matches what you want to participate in as far as the GM's style, type of players being looked for, more about story, more about combat, etc. Be honest in your application too and try to apply to games as soon as possible. You have a better shot typically of getting in if you are among the first to apply. I recommend browsing this forum and using the Join a Game Roll20 tool at least once a day. If you see a game you like and it has been posted recently, jump on applying.