Open Cubase and create a new music project. Select "File" and "New" from the Cubase menu bar. Select "File" and "Open" to select a previously saved Cubase recording from your hard drive.
Drag the selected audio file onto your project window. If a previously saved Cubase recording exists as an external file, such as a vocal recording to which you want to add instrumentation, locate it on your hard drive, and drag it directly onto your Cubase window. It will appear as a horizontal bar with wavy lines on its own individual track.
Create a track for your overdub. The overdubbing process requires the layering of audio regions on individual tracks, which appear as the long horizontal spaces on your project window. To create a new audio track, select "Project," "Add Track" and "Audio" on the Cubase menu bar. Select "Project," "Add Track" and "MIDI" to overdub using MIDI instruments.
Connect any equipment that you will need for your overdub. Connect a microphone for vocals. Connect a guitar cable for guitar. Use a MIDI cable for MIDI controllers. Connect your instruments and other devices directly to your computer with an audio interface, external sound card, or with computer instrument adapters, which are available at music supply stores.
Select "Devices" and "Device Setup" from the Cubase menu. Select either "VST Audiobay" or "VST Audio System" -- different versions of Cubase use different terminology -- when the pop-up window appears. Select your external audio interface, MIDI adapter or other connected device from the list. Select "VST Instruments" from the left column and choose a virtual instrument from the list, such as a synthesizer, bass or percussion sound, if connecting a MIDI keyboard or controller,
Click and highlight on the blank track within the project window, then click the "Record" button, which looks like a large dot. Some versions of Cubase include individual "Record" buttons in the left column of each track, while other versions use only a single "Record" button at the top of the project window.
Record your audio and then press the "Stop" button, which looks like a large square, near the "Record" button. Create new tracks and record using the same process for additional layers of audio.