I need help making an app or website that shows which seat is taken [on hold]

For a project I need to make an app or website that shows which seat is taken but I don't know where to start. It is possible to replace the chairs with a programm where I can enter a chair number and add available or unavailable. Do I need to connect this to a database that holds all the chair information and make the website connect to the database? I know a little bit about web developing, C# and arduino.