How do I specify the JDK in IntelliJ IDEA IDE?

How do I specify the JDK in IntelliJ IDEA IDE?  This is on a Windows OS, not on a MAC.

After I click on the “clean” option under the project’s Lifecycle for version control, it prompts me that “Project JDK is not specified.  Configure…”.  When I select the Help menu option to find out where I need to do this “specify JDK” does not return any search results.