You'll need an audio interface in order to use an instrument or microphone on BandLab. There are plenty of audio interface manufacturers to choose from, but please make sure it's compatible with the device you're planning to use it with, especially if it's a mobile device.
Once you have an audio interface;
- Connect a quarter-inch or XLR cable from your instrument or microphone to the audio interface
- Connect the audio interface to your mobile device (via the micro-USB, USB-C, or Lightning port) or computer (via the USB-A or USB-C port)
- Create a Voice/Audio, Guitar, or Bass track and start recording!