What does multiple inheritance have to do with the code you pasted above?

Here is a list of different examples and tutorials which you might want to take a look at:
http://doc.trolltech.com/4.2/examples.html

Here is an article stating step by step how to use forms created in Designer:
http://doc.trolltech.com/4.2/designe...component.html

Here is a link to The Independent Qt Tutorial by Johan Thelin which is a tutorial on Qt3 for beginners. If you have trouble handling Qt basics, it'll be fine for you even if you use Qt4:
http://www.digitalfanatics.org/projects/qt_tutorial/

The problem is that you're asking questions without telling us what you want. In particular I have no idea what "next step" you were referring to in your previous post. We don't know what you already did, what you're planning to do, etc.