question about coordinate system

I havent read much yet, but would like to know if the foll is possible. I want to set my coord system so that it goes from -180 to 180, and -90 to 90. Then I draw some lines in it. After that I want my coord system to go from 0-100, 0-50, and I draw some sqaures in that, so that I see all lines and sqaures I drew (even though they are scaled differently). If this is not possible I wont use openGL. If it is, what commands do I look at? I know how to draw the lines etc, but none of the simple stuff I’ve looked at shows me how to change my scale midway. Appreciate the help,

You use glOrtho for that. That will set the coordinate system to whatever range you want.

Thanks much for your helpful response.