The following are some software for making background music:

1. **Audacity**: Audacity is a free and open source audio editing software that can help you make music and record sound. It supports multiple formats including MP3, WAV, AIFF, etc. It also has many advanced features such as multi-track mixing, equalizers, compressors, and more.

2. **FLStudio**: FLStudio is a professional digital audio workstation (DAW) that can help you produce music, mix and arrange. It supports multiple formats including MP3, WAV, AIFF, etc. It also has many advanced features such as multi-track mixing, MIDI arrangement and effects processing.

3. **AbletonLive**: AbletonLive is a professional digital audio workstation (DAW) that can help you produce music, mix and arrange. It supports multiple formats including MP3, WAV, AIFF, etc. It also has many advanced features such as multi-track mixing, MIDI arrangement and effects processing.