You will need to apply a technique rather than a specific function or block.
When you get the records in the green block, it starts with records, then there is a list of objects which represents the rows in the table and each object start with a property called id. This property has the record unique number to refer to it later.
So you will need to create another list and add the id to that list whenever you add a record in your list that you show to the user.
The main block includes to fill up both lists
When selecting any item from the List Viewer you will need to use the green block index to get the row ID.
Hope that makes it clear.