edit security in SSRS2008

At the "Home" for SQL Server Reporting Services, when editing via Internet Explorer, one should see a list of project folders. Mousing over any one folder should reveal a dropdown arrow at the right of any one item. Clicking the arrow opens a submenu and in selecting "Security" there one may see/edit the users and roles assigned to the suite of reports. From within a suite of reports, one may click a comparable arrow to get a comparable submenu for a data source. Picking "Security" from this menu will open a screen for configuring how the data source will expose the MSSQL Database holding the tables or stored procedures needed by reports.