critter nation for baby chin

Hi I recently just saved a baby chin.. I've never owned one befor. I went on kijiji and found a brand new double CN for free. But couple prblems, first there is plastic pans. Am I able to just cover the whole pan in fleece, almost like a pillow case? Also he is only 13 weeks old is he allowed in the whole cage I read somewhere I had to block it off and only give him half of it