The Share web application has a special page called Dashboard, which contains windows of content called dashlets. Currently most of these dashlets are Spring Surf dashlets, but they will eventually be converted to Aikau dashlets. For more information on Aikau dashlets, see Aikau Dashlets.
The preferred way of modifying Aikau dashlets is by using Surf Extension Modules to target the Aikau widget that should be replaced or hidden. It is also possible to add widgets to a dashlet this way. The Extension Modules section has all the details.