TestProject.Parent.blow1 = new Coder();
This naming is strange. What are you doing? Are you designing all these classes as inner class of TestProject class? There is something wrong here. You should design your classes as separate Java classes/files if you don't have any special reason.
and one more thing...do we have to edit manifest file or no....may be its something to do with that file.
I guess you mean the manifest file in your executable jar. If you don't need something need to be done via manifest file, you would better not to touch it.
so when i write TestProject.Parent.p1.setVisible(false); it gives me many exceptions...
Tell us detailed information about the exception.
And one more thing. Please use
[code] tag around your code blocks. That will make them easier to read!