Agressive dog that I want in a show?

Ok so my dog is a really cute dog. My friends have commented on how he should be in shows and stuff like that but there's one problem: my dog hates other dogs and tries to bite People who he doesnt know that try to pet him or even come up to him. I dOnt think any judge would want to get bitten so any tips on what I can do to help him become nice? And he's a 3 or 4 year old Cockalier ( cocker spaniel and cavalier king Charles spaniel mix) thanks!