This is the right place to ask questions. When I do repair work for trousers I do it from the inside I place a piece of cloth over the hole to be mended and pin it. On the outside I turn under the torn pieces of fabric to make the hole smooth - you can either pin it or tack it down. I try and use a cotton that blends in with the fabric.
Now if you want to make it stand out as a feature you can place a shredded piece of fabric and make it look like it's meant to be there. If you want to match the other leg or area where it is torn you can place a second patch on the corresponding leg or bottom or wherever.
Then of course there is always an iron on patch and you can buy them from a good fabric store. I always keep a few in case of emergencies. In the picture below it's an iron on patch.
I hope you can understand what I've been saying. Love and blessings Chris
Depending on the age of the boy, and whether or not the trousers are for play or best.....
I would embroider my son's favourite things onto a square of material and stitch the square over the hole.
I would use the darning feature on my machine (or freehand embroidery) and darn the hole using the same colour thread as the fabric.
Obviously patches on play clothes are much more fun! LOLOL!!!
Hugs n gumnuts, Meganne
Yes, patches are just the coolest. Now, I don't mean to be such a newbie...but here is my next question...when you do the first option, do you use the material as stabilizer or do you also use stabilizer? and, could I use the fusible stabilizer in a reversed fashion and then use that 'patch' as in iron-on?