How do I locate an attorney for the following?

The answer to your question depends upon what the contract is for. But most business transactions can be handled by a commercial litigation attorney. You might consider hiring an attorney who will send a demand letter on your behalf as that would be drastically cheaper than filing a lawsuit. You may have to file a lawsuit eventually but it is a minimal investment to send a letter on your behalf as it might be taken more seriously than your efforts to settle on your own. If those settlement efforts don't work out then you would have to file a lawsuit or an arbitration (the location of which could be determined by provisions of the contract). Consider contacting a commercial litigation lawyer who will review the contract for you and help you assess options. There are some lawyers who will offer these pre-lawsuit services on a flat fee basis.