How do i link my sourec code with the widget ?

Hi guys i'm a newbie and i started learning Qt by myself,i design a simple interface to add to number in Qt designer and now i have a problem connecting the widget i designed with my source code i.e a fuction to get two numbers from two lineEdit widget add the two numbers then display the result in the Third lineEdit widget.
Is anyone can help me with this?and there is any documentation online please i need the link to it!!
Regards....

http://doc.trolltech.com/

Just select the version of Qt you are using and it lists out pretty much everything you need. Tutorials and examples are in there so maybe that will help you along the way. Also, the Qt Assistant has the documentation in it as well.

Not sure if that is exactly what you needed but maybe it can get you started.

Thanks,
Jon Jones