Learn how to do the Armbar from Closed Guard.
John Danaher teaches the armbar from closed guard with incredible detail. These fine details will make all the difference especially when fighting a larger stronger opponent where perfect technique is required to overcome strength.
From the guard establish control of your opponents elbow and their head. Bring his elbow to your centerline and then bring his head down. If you can put his forehead onto his elbow. To effect the armbar his elbow must be at least inside your hip. But past the center is ideal. Pulling the head down lift your legs up crossing your ankle high on their back, squeezing and pulling them down with your heels.
If you’ve done this well you should be able to hold the position briefly with your legs. From here raising you lower back off the floor pivot 90 degrees and use your hands to secure the arm. take your leg over their head chopping down with the knee as you squeeze your knees together and raise your hips to finish the armbar.