Crate Training a Puppy?

My dog is 15 weeks old. He is a Yorkie and Schnauzer mix. While I was asleep he pooped in his cage which is located in my room. He has just gotten this cage and he thinks he could poop in it. In his old cage he only peed a couple times. I'm thinking that his cage might be too big, but it doesn't look like it.

I really need help on keeping this new puppy. We have had him since he was 13 weeks old. My mom is already getting tired of him pooping and peeing in his cage. I'm doing a lot of research and taking notes to keep this dog. I'm 13 yrs old. Also my dog was a stray before, if that has to do with anything.

By Sierra D.