Step 1: Get some friends. Or if you already have friends, ask them to join your band (if they play any instruments.)
Step 2: Write some songs. They could be about anything, but since this is a Metal band, you might wanna write something aggressive and angry.
Step 3: Learn to scream without hurting your vocal cords. There are special techniques on YouTube, and MANY of them, that sound awesome. (My favorite scream comes from Marilyn Manson. Listen to The Fight Song or I Don't Like The Drugs (But the Drugs Like Me) or Long Hard Road Out Of Hell.)
Step 4: Schedule some appearances in places like open houses (make sure it's a place where the audience would actually like your music.)
Step 5: Record some stuff. It's real easy to set up a recording studio in your bedroom or basement.
Step 6, and this is the hardest: Look for a nice label. Try to get signed, and try HARD. If one label rejects you, keep trying with different labels. OR OR OR OR you could try and go independent. You'll have to sell your EPs/singles/albums online as digital downloads. But that's MUCH harder, since labels have all the resources for things you'll need, like directors for music videos and ad creators. But if you go indie, keep reading. I mean, Matt & Kim did it and look where they are now!
Step 7: Create your own website or hire someone to create a website for you. I would much recommend that you hire a programmer, lest you want your site to be crappy.
Oh, I forgot, if you don't have (m)any friends who are willing to join your band, you could always hold an audition. Just saying. But get to know people first.
Step 8: Hire some lawyers. Better safe than sorry.
Step 9: Hire some stage designers. They're the guys who make the props and costumes and lights and screens and stuff for your stage and live performances.
Step 10: DEFINITELY post some music videos. Make a bunch of social media accounts (like Twitter, email, BandCamp, stuff like that.)
Step 11: Create a bank account for the band if you decide to go indie, since technically, having a band is considered a business. Then you can wire the bank account to your band mates, and it's easier to pay them.
Step 12: Try and open for other acts before you have your own concerts, just so you'll gather a following and gain some fans so people will know who you are.
Step 13: Start a tour. Your label/manager will take care of that for you, but if you're indie, you'll have to represent yourself and schedule for yourself. Yeah, hard work. But start off small, though.
Step 14: Put out an album. Make talk show appearances, really try as hard as you can to really get out there!
Notes: You can't afford to be picky and choosy about whether the people in your band are male or female, now can you?
Nirvana isn't metal, they're grunge. I'll let it slide this time because you didn't know. :)
Remember, the more theatrical your live performances are, the more expensive they'll be, meaning the more expensive the tickets will have to be, and no one will come.
Make sure your lawyers are good, and budget correctly. Actually, you might wanna hire an accountant for you. Or get a manager. S/he'll do all that crap for you.
Hmmm...What else?
It's not so bad. It is really damn hard work, though. Busy all the time. All. The. Time. You'll have to get up at like 5 AM to catch a plane to tour, plus you have to move all your heavy equipment by yourself into the places you'll be performing, which isn't fun.
Don't let your band mates change your music, but also consider their ideas.
I guess that's it. Good luck! :D