Any time you change environment variable you have to close the current command line interface/command prompt and start a new one for the settings to take affect.
I'm pretty sure that there is no need for anything else to be done or any other software to be installed.
You can verify that you have it installed by opening the command prompt and typing in
gradle -version If you have it installed correctly then you will get a response telling you the version of Gradle that you have installed.
“The strongest of all warriors are these two — Time and Patience.” ― Leo Tolstoy, War and Peace