Web application - Best way for javascript to communicate to a Java server

Hello i'm new to web development and don't know a lot of things yet. I want to create a simple web application for my Internet Cafe and by now I want my PC to be the client and the server. I'm using netbeans as my IDE and using jsp, javascript, and java as my server.

Now for starting things up, I have a login page and I want to send the filled up username and password to server/java. Then run java codes that will look up into my database for match of that received username and password. But I don't have any idea how to do this. I tried WebSocket but I don't think it is build for that or is it?

May I have your best suggestions on how to start on my project and specifically on making a client - server connection. And if you may please add some links of tutorials or documentations that I can refer to. Thanks in advance.