how to update selecteditem and insert into sqlite db?

I would like to achieve an insert similar to this app in the screenshot. basically there are list of exercises there and when you tap one, this pop arises to select the number of sets and when you click add button it will save exercise+set count together as 1 row into sqlite db table. lets say each item in the listview is an exercise object and it has also set property.
When I click an exercise, I can bind to it is selecteditem property on the viewmodel and complete the insert simply but how can I fire that after clicking the button and update selecteditem with set propery, then acomplish the insert all together. because nothing is in the memory to update but only the listview with its items.
I dont really know how to name this case thats why sorry for the title.:)