how to upload image using web services and where images will be store?

First of all, I would like to answer the second question of yours, that is "where images will be store". Well, you specify where the images (or any kind of files) would be stored in the server (specially the hub in your framework). You can even define some third-party to store your data on, by sending the file over to that link and so on.

Now, coming to the main question, the web service is just a framework provided to you to allow you to create a server-client system, in which multiple clients can connect to your application (which acts as a server and hosts your application at a specific IP address) and thus you can (using your client applications) execute different functions and methods on your server. It depends on how you develop the application, you can build a UniversityHub to create a hub for students to manage their details using the client systems (websites, softwares etc), you can define the structure of the web service. Now let us come to the main point, of uploading the files. Well, for that you would require a form (if you're going to develop a website) and then allow the users to select a file and then submit the form to the server. On the server-side, same function would be executed once the call is made, and the file is also attached to the request, thus the server saves it.

It is just the method that you define your actual application's business-logic in. The clients would be able to interact with the system in a way you allow them to. For more on Web Service, please read this Wikipedia article[^]. Secondly, if you're going to create a new web service, and have not gotten into any framework yet, I would like to recommnd that you start using the WCF framework of .NET. If you are interested, then you can read my article[^] on that, and learn how to create a simple web service, and the server (hub) and the clients (website in my case).