Within the “Teams” section, you'll see three tabs: “My Team”, “Lives” and “Chat”.
In the "My Team" tab, you'll be able to see its members ranked by their level, highest to lowest.
In the "Lives" tab, you'll be able to send lives to members who requested them, and request them yourself should you need them. As soon as you enter, you'll see a list of users requesting lives and you'll have to tap on "Help" to contribute. You'll receive a gold bar each time you donate a life.
If you need lives yourself, you'll have to tap on "Request lives" in the lower left corner of the screen. A request to your team members will be issued and, if they help you, you'll receive a life for each contributing member. You'll be able to get up to 5 lives per request in total.
Remember you won't lose any lives for helping other team members and you'll receive a gold bar for every life you donate.
Bear in mind that belonging to a team will allow you to play Tower Duel with its members. If you wish to know more about how to play with your teammates, please visit this article: How to play a Tower Duel with my teammates?