You may have created an Opportunity, or you may have just been added by someone else. As this Opportunity becomes closer to closing, help may be needed on the Opportunity, or maybe you want to add someone to watch. To do so, you will add team members as a resource.
To add a member as a resource, click the share link in the upper right navigation when in an Opportunity, Quote, or Project.
This will open up a modal to invite people to collaborate view. This is all internal people so clients won't see this. You may see yourself as the owner, or you may see many people if others have been invited already.
Add the collaborator by clicking the checkbox for the user you want to add as a resource. And you will then see the two people on this opportunity/project within the bottom right corner of the corresponding tiles.
When a user is added to an Opportunity, they will receive a notification that they have been added as a resource.