HOW TO DRAW ER DIAGRAM USING TOAD

HII EVERYBODY,
I M A NEWBIE,I WANT TO KNOW HOW WE CAN DRAW ER DIAGRAM OF EXISTING SCHEMAS IN AN ORACLE DATABASE USING TOAD.I HAVE TOAD 11.6 FREEWARE.
I ALSO HAVE TOAD DATA MODELER 3.5 BUT I DNT KNOW HOW TO USE TO DRAW ER DIAGRAM ANY HELP HIGHLY APPRECIATED.THANKS.