Audacity is an easy-to-use, multi-track audio editor and recorder for Windows, macOS, GNU/Linux and other operating systems. Audacity is free, open source software.
Download the editor here:
Help with Audacity
How To Use Audacity (5m)
Audacity Tutorial For Beginners
Music for your work
Here are some places to download music. Please pay attention to copyright information.
The BEST Music Licensing Sites