Select Dressing Room under your current character. Select the menu button at the top-left of the screen for more options, and then select Classic Skins. Choose a new skin from one of your already-owned skin packs or select Get More Skins to buy a new one from the Minecraft Marketplace.

How to Buy Items on the Steam Community Market

1
Open Steam.
2
Navigate to Community > Market.
3
Scroll down.
4
Click an item in the popular item list, a game in the list on the right, or use the search box.
5
Click Buy.