How do I add a directory to a checkedlistbox

I have a click button that opens a dialog box. I want to be able to add a chosen directory(or file foder) to a checkedlistbox
when the user choses OK. Not sure how to add the directory to the checkedlistbox. I keep having to select a file and even then it adds nothing. I don't wish for the user to select a file. Just a folder.

My intentions are to put as many folders as I need in the list an later do something with the ones that I check

PLEASE HELP ME!!!!! C#