If you’re a member of a group, you have the ability to add references which can be shared with other members, and also with followers of the group.
Adding materials to a group in Mendeley Desktop is very straightforward. You just need to select the appropriate papers in your library and drag them and drop them onto the group entry in the left hand panel.
You can add single files or multiple items this way.
When using the Web Library, you can add new references to a group by clicking on a paper to select it, and then using the 'Add to' button at the top of the central panel.
Using the popup menu which opens, select the 'Groups' tab and find the group to which you need to add the paper. Select the appropriate group and press the 'Share' button to complete the process.
Once a reference has been added to a group it will be available to users the next time they sync in Mendeley Desktop, or immediately if they're using the Web Library.