How to create data with association in UI in fiori app?

Dear Friends,

        I had create two entity set with association, one is HEADER, another is ITEM.  In my UI, I want to input one header and 

multi-item data, then to sent the data to backend system to create order.

        So How can I finish this though odatamodel ?  Is there any example to help me get this done ?

Thanks for your sincerely answer!