First, remember to post in the correct section , but that's fine that you didn't (you need to post market stuff in the market lounge). Second, to answer your question, you normally want to get some good trades done and vouches first. Otherwise, people won't trust you to MM for them. After that, you should learn how to MM (how to do what, how to send a proper PM, how to confirm everything). Then, go ahead and post your MM thread. Remember to stay professional and make sure everything goes the right way. Good luck!
It's something crazy to start off with so good luck, don't spam around, get trading asap! Try get your vouch count up and make sure you trade safely.
