How do you get a skin for much games?

First of all, if you haven't already, you need to purchase the full version of minecraft to access skins.

There are many sources of Minecraft skins all over the internet where you can download skins from. Do an Internet search for a skin of your liking and download it to your computer.

Once you have done that, log into the official Minecraft website with your account, go to your profile and upload a skin there.

See the related links for a couple of Minecraft skin databases.