Hey how does trading in a car with a blanace of about 12k work with wanting a car with thats 9k?

i've got a 2000 Honda Prelude with 85k miles (with a blanace if $12,000) and i want this 2000 Honda CR-V thats about $9,000 (family reasons) And also my payments right now are $320 a month. would they go lower?