Here are some links to resources to get you started adding audio assets and music to your game.
Music
Here are some places to get music from:
Sound Effects
Epic Sounds has a good guides on how to use sound in video games. Their list of how to create foley effects is useful too.
- Room tone audio can make your game locations feel more real.
- Boom Library has collections of high quality sounds for sale.
- FreeSound, which has – you guessed it – free sounds.
Audio Software
- fmod studio is free to use for indies and works well with Unity. The more you know about audio the better as this is professional grade stuff.
- Audacity is a free open source cross-platform editor
- Garageband is a Mac only music creator.
- fmod is a serious tool for sound designers.
- Here’s a great list of music and sound creation software
Troy of Darc Productions helped me find some of the above sources.