I want to know how should I put it online or on the web that everybody can access to it?
You can either look into an ASP.Net webhost and host your project online (most cost money), so that they can use it interactively.
Or, you can put your project files in an Open Source website, like GitHub. This means that they would have to download the files and figure out how to run / host the files on their own.
solved How can my programme check if the user input is correct or not? [closed]