how to sell a item to user in inventory management system

Here i am going to show you that how to how to sell a item to user in inventory management system, i show you here how you can sell items and during the sell how you can take user info for bill also and moreover you can use this system in multiple environment like how to developed Stock management system in c#,how to developed Sales And Inventory System C#, C# tutorial for build inventory management system, how to developed supermarket management software, how to developed medical store management system