You need to make a character json, there's an example in the repo.
Someone is putting together a guide here: https://docs.google.com/document/d/11Y5PsGso09mGWIV5R8q5yPtwpV51Erjtz_esTg-oOAA/...
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Just to highlight it, this guide includes this link to a few example characters to try out! https://drive.google.com/drive/folders/1BZfgkkn6Aj5Uh0RW-N_jWKe6iGBlSGQl?usp=sharing