Garrys Mod - E2

Im trying to learn E2, By myself. i started out making holo’s Seems Easy Enough. i been making some hats, but i saw somone who made a pair of glasses. and i dont know how to do that, i made the holo, i got them on my face, by their all jumbled up cuz the angles arnt right. i dont know how to rotate the anlges of the holo independently from the face, while still keeping it attached. anyone know and can help? id be very thankfull