A win boost in Teamfight Tactics is usually played solo: the booster logs into your account and plays the ranked games while you take a break. Unlike team games, there is no shared duo result here, because every player in a lobby builds and places with their own board. Standard ranked does allow small parties below Master, but each of you still finishes with your own placement, and Double Up is a separate mode with its own rating. The order form also has a Play with booster option, in which you queue together and play on your own account, but only your own placement moves your rank, so agree in the chat on what counts toward the order before you accept.
If you want to stay at the keyboard and improve at the same time, the alternative is live coaching. You play your own ranked games while a high-rank coach watches your screen and guides your levelling, rolling, item choices and positioning in real time. Your rank then moves with your own play, and you keep the knowledge afterwards. Many customers combine the two: a short win boost to recover momentum, then a coaching session to hold the new level.
Before you post the request, check your exact current rank and division, and decide how many Top 4 results you need. Add everything the booster should know in the notes: compositions you would like them to play or avoid, how cautious or aggressive you want the games to be, and whether they should keep chat quiet. Name your region and server, so the offers you receive come from boosters who play there. Also write down the hours when you want to use the account yourself.
After you accept an offer, watch the chat for the first minutes, especially for a possible verification code at the first login. From then on the order runs by itself: the booster reports each counted Top 4 in the chat, and it appears in your match history. When the ordered number of successful games is reached, the booster marks the order as completed and you confirm the result. Change your password, and your account is ready for your next climb.