It would be helpful if we could see your code. I am not going to do anybody's homework for them, unless you are willing to do my linear algebra for me.
When you create a project in Netbeans, it will open a panel on the left side with your project. Onbe of the tabs will be labeled 'files'. If you click on that one, and then expand your project, you will see a directory called src (which stands for source). That is where your source code will go. All you really need to do is right click on the project name, select New, then class (or Main Class, depending on what you are doing), then give it a proper name. Once you do that, the project will open in the editor, and you can go about creating your project.
Post up your code so that we can see what you are doing. It would also be helpful if you stated what sort of errors you were getting.