VS 2010 how to add item from datasource combo-box to listbox ?

hello
good morning
i follow those steps :
1 - add data source
2 - insert it by details and choosing combo-box style
3 - i add listbox and button

i want to choose from combo-box item then click add button and it will inserted into listbox
how can i do that ?

http://s14.postimage.org/9yylzltkh/datasource211.jpg