How to see if the checkbox is checked in pl/sql

I need some help, I am relatively new to Apex. I have made a classic report on my page and this is the part of the sql query that is used for making a checkbox field in report

select APEX_ITEM.CHECKBOX(1,IDACCOB,'UNCHECKED',null,null,'f10'||'_'||lpad(rownum,4,'0')) checkbox... from accob..

As you see idaccob represents the primary key of the table, and I would use it to fill the fields in tabular form with the data from that row. Now, the user has a possibility to check or not to check the checkbox for every row of the report. What I want now is to see for which rows the checkbox is checked so that I can use some of the data from those rows of report and to put it inside some fields in tabular form on the same page. After the user checks all of the rows that he wanted to check, he clicks the button, and some of the data is transfered(copied) to the tabular form. I want to complete this action by using dinamic actions, and execute PL/SQL code. I know that it will have to go through for loop, it is not the problem, but I don't know the syntax or how to access the status of checkbox.

I will be very glad if any answer comes up :)