Get the hWnd of all screens the pc uses.

I am working on a screen capture program and in a loop, i need to get all of the hWnd of each window on the pc. For example, i have four screens i use with my pc. So in the loop i could get the hWnd of each screen. If i am on a pc with only one screen then the loop would only run one time.

I am currently using GetDesktopWindow but that only allows me to capture screen 1.