You don't have to calculate anything
Just make sure you do glMatrixMode GL_MODELVIEW (or whatever it is - might be glMatrix()) to select the modelview matrix, then do the glloadidentity() and the translates/rotates. It affects everything drawn after that point, so after you'd done the sprite, either do another sprite or reset the modelview matrix to the identity matrix with loadidentity() again.
This is basic stuff - go read the OpenGL red book and blue book online.
Just make sure you do glMatrixMode GL_MODELVIEW (or whatever it is - might be glMatrix()) to select the modelview matrix, then do the glloadidentity() and the translates/rotates. It affects everything drawn after that point, so after you'd done the sprite, either do another sprite or reset the modelview matrix to the identity matrix with loadidentity() again.
This is basic stuff - go read the OpenGL red book and blue book online.