To assign permission groups and or individual permissions to teammates follow these four easy steps:
 
Step 1:
Org Menu>Teammates

Step 2: You will see a list of existing teammates here, click on the teammate you would like to give a permission group to:

Step 3:Select 'Permission Groups' to see which permission group they have been assigned. (Note: you can also select : permissions, to see permissions at a granular/specific level)

Step 4: Here, you can toggle/on off permission groups to assign permissions in bulk to this teammate. You can also click on 'permissions' next to 'permission group' to assign specific permissions to this teammate as well.