Using the Behringer MX400 line mixer is easy. First, connect your audio sources to the appropriate channels using the input cables. Then, adjust the input level for each channel according to your needs. You can control how much audio from each source gets mixed. The power adapter is included, so just plug it in to power up the mixer. When using it, make sure to place it on a stable surface to avoid any accidental knocks. Keep it away from liquids and extreme temperatures. For maintenance, you can use a soft, dry cloth to gently clean the exterior of the mixer. Don't use any harsh chemicals or abrasive materials as they could damage the unit. That's all you need to know to get the most out of your Behringer MX400 mixer.