Where is Gradle support?

I am using IntelliJ community 13.1.4.

I created the project by importing the source ( no build file: no ant, no maven, no gradle).  Now I created a build.gradle file with a single Spring dependency & tried to build from within IntelliJ but got the error message.  Error running buildModule 'Force' is not backed by gradle"

So I searched on that and was directed to link the project using the "Gradle Window"  View->Tool Windows->Gradle Window

Gradle Window is not an option under the Tool Windows; how do I make this work given I did not originally use a build.gradle file to import the project.  I want the project from within IntelliJ to now be managed by gradle (as I add new dependencies).