Out of my league!

My boss is asking me to figure this out and I'm trying but I feel it's just out of my league!

I need to automatically cross-reference the "Equipment Serial Numbers" and have the corresponding "Customer Name" from Sheet 1 show up under "Location" on Sheet 2. If there is no corresponding "Customer Name" on Sheet 1 I need it to show "In Stock".

The "Equipment Serial Numbers" on Sheet 1 are constantly changing as we install/remove equipment and I need to keep track of our inventory all in one place, automatically.

Please help me impress my boss!