You will need some tools; a hobby knife and a covering iron at a minimum. You will also need some glue and probably some ultracoat too. It may be as easy as opening up the covering where the ribs are broken and gluing them back together using CA or even a white glue like Elmers. Then patch the hole with the Ultracoat that you will acquire, using a covering iron. If the damage is such that you have to make new ribs, or a least a part of a rib(s), then you will need some balsa wood too so that you can use your hobby knife to make a new rib part that will replace that which are damaged. Then just glue them in and make your patch.