Mendeley currently offers you a number of ways in which you can share your documents with your colleagues, or other Mendeley users. Depending upon what your needs are, one method may suit you better than the other.
Private groups are great for if you wish to share a document amongst your colleagues or lab partners. With a private group, you can upload files to which only a selected set of people have access to. Each member can collaboratively contribute to this group too - adding new papers, updating document details and by annotating and highlighting PDF files.
Currently, private groups are limited to 3 members - however as part of a premium subscription package, you can extend the size of your private groups.
If a private group sounds right for your needs, you can read more on how to create one here.
Private groups were previously known as shared collections.
If you wish to simply publish a reading list, or set of recommended or related papers, public groups are ideal. Through the use of a public group, you can drag and drop files into the group and anyone can subscribe to it to receive updates as and when you make changes.
You can add other Mendeley users as members of the group, and they can help you curate a reading list, or you can create a totally open public group that anyone can join.
Files attached to documents in a public groups will not be available to the subscribers or to the other members, these groups are only for creating reading lists. Only you and the group members will be able to make updates to this collection that all of the subscribers will receive.
You can create two kinds of Public Groups, invite-only which has a restricted membership list, and open, which anyone can join.
If a public group seems to be the right fit for the task, you can read how to create one here.