"TheLegendary117" gave a decent answer, but there's a few things I think I need to point out, just so you know what you're up against.
First of all, the way ranked matchmaking works in this game , will not be able to search in a team of 4. Team's of 4 must match other team's of 4, and NO ONE searches in 4's anymore due to the age of the game. You will only be able to search with one other player in your party and still find a game.
Also, you have chosen an unfortunate playlist to do this in. Team slayer is absolutely INFESTED with cheaters at 45+, since no one polices this game anymore. If you do go thru with this be prepared to be booted offline, face aimbots, face jtags (ppl flying thru the air, unlimited ammo etc.) on a fairly regular basis.
I also looked at your stats and saw you have 2651 EXP. That is NOT GOOD bud!! This account used to be my screw around account, so when I finally went to get my 50 on it 2 years back, I had about 2000 EXP and probably 3000 games played. The thing is, the more games you play in h3, the harder it becomes to rank up. That's why most people will make new accounts for this sort of thing. Anyway, I did manage to get my 50 but the amount I had to win to rank was absurd. Going from 48-49 took me around 35 straight wins with no losses. 49-50 was slightly easier, as I managed to rank up with "only" about 40 wins and 5 losses. You have more EXP than I did however, so it will be even worse for you...
Honestly, I'm a bit skeptical of your ability to do this, and I don't say that to be an -Yoink- but to give you an honest assessment of what you're facing. If you can't get above 45 on your own, you're gonna have a tough time when your around 48 and needing to win 35 or more games in a row to rank up. Not that you shouldn't try, but it's gonna be a hell of a fight.
Anyway, I'm retired from TS myself but I do still enjoy a game of dubs as cheaters are far less common. If you ever feel like running team doubles just send me a message and I'd be happy to run with you.