Virtual Blocks in openGL

I need to create a project for virtual blocks in openGL. I’ve never coded ANYTHING in openGL before (this is for a school project, and my two groupmates have left me with all the work, unfortunately).
Anybody have any ideas (vague or specific)? My idea was to have a “plate” of say about 100 by 100 at the bottom, have a top view of it, and let users “drag” out where they want to place the block and hence the size. Was hoping I could use an array to keep the information. I would appreciate any help as I have no help from my prof or group mates and I have never coded in openGL before, OR visual c++! Thanks!