I recommend that you save it into a folder which you can use to store your programs. Try making a new folder in your hard drive, like this: C:\MyPrograms.
After you have created your project, it will show in the Package Explorer on the left. If you click on it, you'll see something called src. Right-click on src, scroll over New, and select Class. Name your class "HelloWorld", and click finish.
1そうだね 未プレイ