I need some help for my homework?

I need some help for my homework?(please fix comma/punctuation errors : When Freddie was young his parents took him to London England Paris France and Milan Italy. Julie and Carl practice playing banjo because they are in a band together and they want to become famous musicians.)(please fix the point of view shift error: When I went snorkeling off the coast of Belize, you could see sharks in the water. People need to be careful when swimming along the coast because you could get stung by a jellyfish.)