Do you mean "seam bound-off shoulder seams"
do you mean "sew on the sewing machine..."
If you mean "seam" the shoulder seams...use the mattress stitch to seam the bound-off shoulder seams together. Butt them together on a pillow on your lap, or on a tabletop...put a couple little pins to hold them butted together...and do the mattress seam.
Yes, there is a video clip here at KH for mattress seaming.
Go to VIEW VIDEOS>TIPS>scroll down to FINISHING>scroll down to Mattress Stitch.