Use the Add Player button on the roster page. Each player you add will receive an e-mail with their login details and unique randomly created password which will allow them to login to their own BenchApp account.
Once they log-in for the first time, they can create their own unique password.
If you add a player without an e-mail, they will not receive any login details. If you then edit this player and enter their e-mail, login details will then be sent.