How is the best way to sell software Intellectual Property and Source Code?

I am partners in a company that has a software product for the K12 education market that we are looking to sell to an interested buyer. We write great software, but don't have a lot of expertise in the marketing and sales end of things, and the contract we had in place with a sales organization has been cancelled due to lack of performance on their part. We would like to place the source code and intellectual property on the market, but don't know where to start.