1. Goto Manage Attributes
  2. Find the attribute you want to showcase and click on it 
  3. Set the value of "Use In Layered Navigation" as "Filterable (with results)"  and "Use In Search Results Layered Navigation" as "Yes". Save.
  4. The configuration change will be updated in 24 hours else do a manual synch to transfer the updates. We recommend you do a manual synch during a time of low traffic.