Piece of cake, Paul. A nice little hole like that one is great way to learn sewing, too. I assume you know how to thread a needle and tie the ends together. You should only need 18 inches of doubled thread for such a small hole.
For inside pockets, I like to use a "continuous loop." Push the needle completely through one side at one end of the tear, pull the string half way through, then pass the needle between the tied ends of the string to lock in the first loop.
Pull the string tight, then just loop around the outside edge and push the needle through the same side, but an eight inch further down the tear. Keep that up until the hole is sealed.
You'll have it sewed up in less than a minute.
Oh. Be sure to pass the needle under the loop a few times at the end, to knot the string tight. Then simply cut off the thread close to the knot, and you're done.