How to Open a 2d UI to display 3d object?

I developed a little 3d rpg demo use opengl2.0 with terrain and sky.
also I rendered a 2d dialog use opengl to display the role info including the 3d role model and skill level etc.
but when I dragged the dialog,the 3d role model cannot move together with the dialog.
I have been confused for 2 days. can you give me a help? thank you