If the home is worth more then you owe, no problem, list the current home, once sold you can pay off the current home and purchase another.
If the current home is worth less then what is owed. Then your "under water" and you have a few different ways you can go. Give my office a call and we'll guide you through the process.
Rixon Realty Inc.
See if you'll qualify to hold onto the old one while purchasing a new one.
Take an equity line on the old one to purchase a new one.
There's lots of things you can do. Really depends on your intentions/plans for the old.