You need to launch the designer, click File->Setup NetBeans and select netbeans.exe/.app.sh file from the NetBeans bin directory so the designer can trigger NetBeans.
You can create a handcoded application in the Wizard (second option on the bottom) where the designer is only used for the theme and not the GUI. You can handle events just like you do in Swing/AWT addActionListner
etc. on any component.