To add audio, click the Animations icon on the left side menu. Then, under the Audio section, select Import Audio. Choose the file from your device and it will automatically begin importing. Once complete, you should see the name of the file:
We support most audio files including AAC, AC3, AIFF, FLAC, OGG, OPUS, MP3, MP4, M4A,TS, WMV, WAV and WMA.