In the ARRANGE WINDOW, highlight your last AUDIO track. Go to TRACK menu and select CREATE AUDIO TRACK. You can double click on the default name ("Audio") to change it. Go to the box and the left side of your screen. Click on "CH" (or "CHA" in Mac). This will create a channel in the onboard mixer. Select a channel number from the pulldown menu that appears. Now go to the Windows menu at the top of the screen and select Open Mixer (In Mac it's called Open Track Mixer). Select your input channel for your new tracks by clicking the Input field above the Pan knob, and selecting one of the eight possible inputs that appear in the pulldown.