Any entrepreneur needs to learn sales, because you will need to sell your vision to your employees, yourself to your investors and your product to your customers. While the first two are all about self confidence, the third is the one you asked about.
Selling is like swimming... You can read a lot of books about it, learn about hydrodynamics and what not, but until you jump in the water, you are not going know how to swim. To keep the analogy going, you might not want to jump off a boat in the middle of the ocean and start swimming to shore as you start... Start with a teacher and a lifeguard near by... Start by selling other peoples products before trying to sell your own. One class of product that I generally resent but can give you great experience is MLM (Multi-Level Marketing). You can learn to sell that junk to strangers with little personal financial risk, and they will teach you courses on sales for almost free (just your time and maybe a small initial investment).
You can either gain the experience you need, or partner up / hire someone with that experiences. If you have the tech background that is needed for the business, you might want to focus your attention at that, and find someone else to take care of the sales/marketing/business end of things, since a good CTO is also critical. Keep focused on your core competencies, and you will do well.