LMMS

It is an excellent open-source program to create music tracks using sound files, predefined instruments, and sound effects. The software is designed to streamline the music-making process with a computer to get new users into music composition as quickly and painlessly as possible. Their feature sets include preset audio loops, MIDI tracks, and other ready-made musical materials available for immediate use in a piece. Their GUIs invite involvement in making music, and it's clear that the designers want the user to have fun with the program and the process.