This is a basic setup for a triangle from guard. It is a slow setup that is suitable for beginners and works better with a gi than in a no-gi situation.
Ming is in my guard and defends by pushing my hips down with his hands. I grab both of his wrist with my hands, bridge and pull one hand up and push the other down while dropping back. The bridge works first as slope that makes it easier to pull Mings left hand up and then provides an opening to push his right hand through, when I drop back.
As soon as Mings right hand is out of the way I reach accross to his ellbow to pull it accross my centerline and at the same time cut down with my left leg perpendicular to his neck. Note that I rotate slightly to my left to achieve the proper angle for my leg.
I secure the position by grabbing Mings head and then lock in the triangle. Provided that the opponents ellbow is nicely accross my centerline and the leg is perpendicular to the neck, the triangle is usually tight enough to get a submission simply by squeezing the legs together and down. If this is not suffient, pulling the oppenents head down should do the job.