To use the ETC Unison DR12 120V dimming rack, first make sure it's properly connected to your lighting system. Plug it into a 120V power source. You can then adjust the dimming settings according to your needs. When using, avoid overloading the rack. For maintenance, keep it in a clean and dry place. Regularly check the connections to ensure they are secure. If you encounter any issues, consult the user manual or contact customer support.