Drag&Drop without freezing in C#

I'm newbie in C#. I tried to use background worker for drag and drop files to a listView, but I don't knowwhat to write in DoWork. as I saied before, I'm a newbie and try to make it without background worker. when I tried to drag alot of files and drop to listview, while adding file, I can't cancel opration and operation must be completed to I can use my app. there is something happened like freezing. can anyone help me?

thanks.