Updating a workspace will get the latest files from the server. After another user has submitted a change you need to 'Update to Latest' within the workspace to incorporate the changes.
To update a workspace within Eclipse, right-click the project and select 'Team | Update to Latest'.
You can view any PureCM messages in the 'Console View'. The update will fail with errors if there are conflicts (i.e. you are editing a file which has been updated). In this case you must resolve the conflicts using the PureCM GUI or 'pcm' command line client.