I know! It's like telling an obese guy that he needs to run outside. For being able to provide a valuable product to international academic institutions, alone, from a beach house, I am good at many things but sales is definitely my weak spot.
Start by deeply thinking though the problem that you current customers have and how your software solves it.
You must know other schools that are similar to your current schools. Where can you get a list / LinkedIn? / Government ed sources / Buy a list.
Write materials to contact these schools / emails / newsletters. Keep cold contacting them every 3 - 12 months (unless they ask you not too).
For groups who response with queries, setup time to show them your solution. Give them testimonials.
If they ask for a sales pitch, then offer to quick config your solution to their local needs.
It's a process of talking to potential clients, discovering and understanding their problems, and considering how your software could be a solution. It is a conversation.