Click on the project in which you want to add a group of members from the general navigation bar :
Then click on Team on the white menu to the right of the navigation bar :
You will then arrive at the intra-project resource management view :
To edit a team in your project, click on to the right of the team concerned then click on "Edit" :
You will then be able to:
- Rename group
- To modify the resources that are part of it
Click "Save" to complete the operation.