You can make your own items and put them in the Catalog for other players. Press Create on the website and pick what you're making.
Use the classic 585 x 559 template, as a PNG, JPG or WebP picture. A picture of a different size is fitted to the template for you, but drawing on the real template looks best.
Any picture works. It goes on the front of the character's torso.
Faces are a picture on the front of the head. Heads change the shape of the head itself.
There are three ways to make a hat:
After uploading, Edit hat properties on the item's page lets you move, resize, turn and recolour it.
Uploads are checked before they show up for everyone. Keep them friendly and make sure they're your own work. See the Rules.