Re: laptop usage application
Helpful articles for you:
Login Page: If you want it to come on when the laptop starts, you will need to load it as a Windows Service (assuming you are on windows). I don't think you can do that natively in java, but there is a tool you can try out: Java Service Wrapper - What is the Java Service Wrapper?
Using the System Tray (if that is what you are talking about when you say "a small icon on my desktop"): How to Use the System Tray (The Java™ Tutorials > Creating a GUI With JFC/Swing > Using Other Swing Features)