“She shed”

My niece has seen the “she shed” commercials and now she wants one lol! My husband built us a shed last year and she wants one just like it, her mom says it’s a good idea and we think so too! Now I want one lol! My question is how could we decorate it? She wants to “live on her own” for a night and have a sleep over in it (with mom watching her of course) she wants it like a real house. I just don’t know how to decorate things because I’ve never been creative.