NetBeans Platform Main Frame

I am looking into the NetBeans platform for devel开发者_开发知识库oping desktop applications. I am a complete newbie in it. I understood till now the module architecture. Now I want to do some GUI work. My question is very simple and feel embarrassed to ask it, but how can I edit the main frame of the application? I mean the one generated automatically by NetBeans. I looked around but for god's sake, I can't see it in the IDE:(

Edit: It seems there is a misunderstanding. I know how to create a JFrame:) I am talking about the NetBeans platform, when your application is built on top of the NetBeans core. Here is a short article. At the bottom there are two screenshots. The IDE generates a Main frame looking like the real NetBeans IDE. I can create new modules and so on. But I want to edit this Main frame, but I don't see it in the IDE. Hope my question is clear now.

Thanks in advance:)

Regards, Petar

As I learned more things of the NetBeans platform, I understood that there is a virtual FileSystem which is build from combining layer.xml files from all modules. This FileSystem is the configuration of the application. It includes things as which menu items to be shown on the main frame, etc. So I guess the main frame is edited this way:)

Yes, is like Petar says, but to be more specific, one way to do this is from the Netbeans GUI is described here. http://platform.netbeans.org/tutorials/70/nbm-htmleditor.html#tweakingthemenuitems. This is for 7.0 version of netbeans.

I found useful this question also How to remove items from menu in netBeans platform?.