Where to find product key or activation key on Windows 7 Home Basic

[frankglo]

I have an old Dell laptop which I use for streaming audio only.
There is Windows 7 Home Basic already loaded onto the laptop, and the person who had the laptop previously did not load a genuine Windows 7 Home Basic software. So I am seeing "this copy of Windows is not genuine" showing up all the time.

Now I have a genuine product key or activation key for this Windows 7 Home Basic, but I am at a lost.
How or where do I put in this product key so this message could stop coming up? I went to Control Panel, System, and there is nothing there that says "change product or activation key"

Help

[dishuser]

system/see the name of this computer/change product key

[frankglo]

system/see the name of this computer/change product key
See the name of this computer and view amount of RAM and processor speed are the same.
Both do not give indication of where to put in the product key.
Advise

[dishuser]

at the bottom it has windows activation and beside product id it should have enter/change product key