If you are in the group details, to which you have access by clicking on the group name in the left hand menu panel.

You may now hover your mouse over the Members button that is located in the upper right of the screen, which will show you the complete list of members. Click the Add members button at the bottom of the list.

A modal window is shown with the group name at the top, so you can double check you haven't mistakenly clicked on a different group.

Now you can start typing your colleagues’ names and our autocomplete feature will speed up the process for you. Click the Add members button and that's it!