You've built a product. You think it is ready for real users. How do you find out? You do usability testing. This is a specialized discipline, and there are specialists out there who know what they are doing. You should hire one of them to do usability tests on your product. They will do a much better job than you can, and you will get much better results. But if you can't, you can do your own usability testing. I've written up my understanding of the subject: Usability testing on the cheap.