First you'll want to remove the extra piece from your sewing machine if possible. The smaller the jeans, the harder it is to get in the leg and move and turn as you need to.
Next, you'll want to cut all the strings that are hanging in or around the hole.
Now, measure the size of the hole, so you'll know how big of a patch to cut. I like to allow myself about 1/2" on each side of the hole.
So for this hole, I would cut a 4" X 2" patch.
Cut out your patch. Turn the jeans inside out, and pin the patch over the hole.
Sew around the outside of the patch.
Turn jeans right side out, and trim a diagonal on to each corner.
This will allow you to fold each side under.
Finally, fold raw edges under, and sew around the hole.
The larger the jeans, the prettier they will look. These are my five year old boys pants, and I will not even attempt to do any smaller!
If it's a smaller hole like this:
I simply turn them inside out, and reinforce them with a patch.
This is what it will look like right side out.
And now, this little wild boy, has some play jeans! Unfortunately, he tries to wear his patched jeans every day, and we have to have a little talk about that when we're going to church! I don't mind so much if he wants to wear them to school though, as long as he's clean!
I hope this will help! Good luck, and feel free to e-mail me with any questions!