It might sound a bit obvious but to start with you need customers so first and foremost find out where they are. Talk to prospective purchasers, find out what events they attend, what networking groups they are involved with, trade organisations and buddy groups. From this information build your 'ideal customer' profile and along the way you should have collected contact details of many more prospective customers as well! This will also help identify whether there is a market for the product and acceptable price points.
Next on your website create an incentive offer such as 'try the XX product FREE for thirty days' or provide a light version free that has limited functions with an ongoing upsell to the main product. then contact affiliate platforms and invite their publishers to promote the offer.
Contact me if you need further assistance in developing the strategy.