The main character from Bioshock Infinite.
Designed by John Doe
You can go to category skin to find & download skins. It doesn't matter where you save your skins, as long as you remember the name of the folder. Also, if you change file names, it'll make it easier to organize your collection.
Once you have your desired skin, go to your profile on the official Minecraft website. Click on Profile and log in with your Mojang account (the username is the email you used to register).
Once you're on the profile page, click the Browse button and browse through the folders until you find your skin. After you've selected the skin, press Upload and wait for the confirmation message.
4. Enter Minecraft and try out your skin
Now, all you need to do is enter Minecraft; if you're already in the game, leave and then enter again. After that, just load up a world (it doesn't matter which) and press F5 to see your new skin. Quite a change, don't you think?