myBill is written in Java and uses internally hsqldb which is an open source RDBMS written also in Java and is included in the distribution zip-file. In other words there are no other requirements besides the Java VM. If by any chance you have not Java installed to your system, you can find it here
myBill needs no installation except downloading the latest zip file, uncompressing it and executing runApp.sh if you are on a unix-like OS (like Linux,*BSD,MacOS) or runApp.bat if you are using an MS windows flavor.If by any change the program does not start in Windows when you execute the batch file, try double-cicking on the jar.
If you are still having problems starting the app, that means that your java installation is in a quite different place than the one used in the development systems, so you can start the app, by just typing the command "java -jar myBill.jar" while being in the project directory from a command or DOS prompt depending what type of OS you use.You can download the zip file from here. Of course that means that you can use your copy from any kind of portable media like a usb stick or an external hard-drive.