This move is good for a small person to use on a big person, because once you are on somebody's back, size doesn't matter at all.  While it is done explosively, it does not take much strength.  When a fighter is good at the arm drag, it forces the opponent to use a lot of forward pressure to try to put him flat on his back.  This forward pressure can be used to set up sweeps.

1. Jimmy is in my butterfly guard grabbing my pants at the knee.  I can't allow him to do that because it's a strong position for him to pass my guard.   Since Jimmy is sitting back and not putting his weight on me, the arm drag is a good option. 

2.  I grab one of his wrists with a two on one.

3. The grip is like you are grabbing a baseball bat.

4. My right hand is grabbing with my thumb and middle finger wrapped tightly right around the place where the Jimmy's hand and forearm meet(The pic is not quite correct, it should be a little more down towards his hand).  Think of Spiderman shooting his web out: the thumb and middle finger are touching and the other fingers don't matter as much.

5. I take my left foot out and stomp it forward and to the left, as I pull with my baseball bat grip back and to the right, breaking the grip on the pants.

6.  I grab his tricep up as high as possible by the shoulder.

7. I drag him across my body.  This must be done explosively, throwing him forward as hard as possible.  It's not done by using my arms.  I twist my body to the right and drop my right leg flat on the ground.  A lot of the power comes from my left foot posted on the ground.  In this picture I'm leaving more space than I should, in order to show how he is dragged across.

8.  With my left hand I immediately grab his hip.  This will help to stop him from rolling over onto his back.  However, if he does manage to roll over on his back, that's still pretty good, I got a sweep.
(not shown in photo) From here I should immediately try to put my chest over the middle of his back.   First, if he tries to roll to his back, he'll just take me with him, still on his back.  Second, if he tries to put his hips up in the air, he'll just lift me up on top of him.

9. As I do the drag, I need to make a hip movement forward and to the side, so my right knee pit is hugging his knee.   I'm leaning my upper body away in the picture so you can see that part.  Of course, you wouldn't normally lean away like that.
Reasons why I need to do this movement:
a) If I didn't manage to drag him forward( if he leaned back really hard), then I need to move forward to him.  
b) If I move forward as I drag him towards me, then I get to add our speeds together, and it seems to him like I'm moving twice as fast. 
c)  Most important, if I can get to his side very strongly, so he can't face me, then he can't put me flat on my back.  If he can put me flat on my back, he can do a lot of escapes or defenses, so I don't want that.   When I'm on his side, as opposed to facing him head to head, it makes it much easier for me to get up off my back and get on his back.  If you do end up flat on your back, keep scooting down towards his legs, and get your legs in this position.

10. If I pulled him forward really hard, then his hands will be posted on the mat.  If he didn't post his hands on the mat, he would have rammed his head into it.  The first thing I'll do is start choking him, because he can't defend; his hands are on the mat.  This will let me get my choke in deep, and will make it easy to get my outside hook in because he will be defending the choke.

11. As he defends the choke, I throw my other hook in and finish.  It's important that if you do this right, you don't have to mess around for minutes trying to break down his choke defenses.  In that instant his hands were posted on that mat, I should have been able to get my choke in really deep, and I should be able to finish quickly.