Chat is only available in the app, you can download the app from the App Store for iOS or the Google Play Store for Android devices. By Default, there is an All Team Members (and All Team Admins for admins) chat created for your team. This is a chat for all players, parents, coaches, etc that are on the roster.
Create Chat in the App
Press Chat in the bottom menu bar
Click the '+' icon to add a chat
Select the recipients of the chat
Name your group and press 'Create'
Your new group will now be visible in the chat section. For chats that you are the owner of (or if you are a team admin) you can make edits to the chat by clicking into the chat and clicking the Gear Icon in the top right.