How to get selected rows from Classic report

Hi everyone,

I'm using APEX 20.2 , I have classic report with Items to order where i used checkbox column(APEX_ITEM.CHECKBOX2) to select required items.

after selecting i have to move the selected rows into collection when click on button, how to get the selected rows into collection. what is the default  checked / Unchecked values of  APEX_ITEM.CHECKBOX2?

Any help would be highly appreciated..

but when i click on button after selecting rows , the selected rows are not moving to collection