If you're looking to upgrade your progressive PUBG skins, there are a few things you'll need to do. First, you'll need to purchase the next level up of skin from the in-game store. Once you've done that, head into your inventory and select the skin you'd like to upgrade. From there, click on the 'Upgrade' button and follow the on-screen prompts. You'll need to have the required amount of resources in order to upgrade your skin - so make sure you've gathered enough before attempting it!