Reminder and notes in Java SE Files

Compilation
You must have Java Development Kit 1.7.0_01 installed. 
Open a terminal/command prompt.
Navigate to the directory where you downloaded the source files.
Run javac Reminder.java


Running the application
You must have Java Runtime Environment 1.7.0_01 installed.
Open a terminal/command prompt.
Navigate to the directory where you downloaded the compiled files/ where you compiled the source files.
Run java Reminder
Application icon will appear in your system tray.
Have fun.

For best use add a batch file (running the application) in your startup directory in Windows / a script to the startup applications in Ubuntu.
You can also create a jar file and run the command 'java -jar reminder.jar' (supposing your jar file name is reminder.jar) in the batch file/script. But this application requires file writes, and the jar won't allow modification of its contents. In such a case if the jar is tried to run the files for storing reminders and notes will be created outside the jar for modification.