You need to setup a SDK for Java projects, like @rizzletang said, but you don’t need to create a new project, you can do it from the Welcome screen.
On the bottom right, select Configure > Project Defaults > Project Structure:
Picking the Project tab on the left will show that you have no SDK selected:
Just click the New... button on the right hand side of the dropdown and point it to your JDK. After that, you can go back to the import screen and it should just show up.