> *Does anybody know how to change the initComponents() method?*

You cannot directly, you have to modify the properties by selecting the
items in the tree on the right.

> * *
> *For example, in a JTabbedPane, when using Form Editor, I can never
> change the labels Tab1, Tab2...Tab#*
> **

Suppose that you create a JTabbedPane with some JPanel inlcuded. You
have to select each panel, go to the "layout" tab under the tree and
change the "tab title" property.