You can learn what teams are and how you can create them in a workspace by following this article: Creating teams permissions in a workspace.
When teams have been created in a workspace, you can add the teams to an item's permissions by doing the following.
- Navigate to the relevant item
- Scroll to the bottom and under the Actions menu, select 'Modify [Item type] Properties & Permissions'
- Open 'Permissions'
- Choose 'Managers + Teams' from the drop down on the permission you want your team to have.
- Click In the text box that has now appeared and you will see all the teams appear in a drop-down.
- Select the team to add it. You can add as many teams as you want to each permission.
- Select 'Save' at the bottom when done.
For folders, you can tick 'Copy Permissions', if you want these same permissions settings for everything contained within the folder.