Can I make a rabbit hutch, from our swing set?

So we have this tree house thing on our swing set, and it has a wooded in area where there are little pebbles. How would i go about turning this tree house half into a rabbit hutch. I know I would take out the pebbles, and then should I grow gr down there or what? Sorry if this didn't make much senses, but it's "two stories"so the top would be their real hutch then they would have a ramp leading down where there may be gr for their run. How would i go about making this?