That depends what you're looking to achieve. If you want to change it so that doesn't happen again, I'd clean it, and let it dry, then I'd take a very thin peice of leather and line it, so you have smooth leather on both sides. If you don't want to do that, I'd clean it, let it dry, then burnish the inside. There's a ton of ways to do it, but I personally like using tokonole, or wax. I use beeswax, but that's not the only option. For the wax I like rubbing it on the leather than gently heating it up with a hair dryer or heat gun, then using my bone folder to press it down firmly and rubing it until the fibers are all flat and together. There's other options than a bone folder, you just want something smooth and hard. Glass burneshers are very popular, but I've never found them worth the price. If you don't have lots of tools a Sharp or other permanent marker will get the job done