Change location of LR library

I had a computer issue and had to send it out to be fixed. Previously, I had all my LR files on my E drive, but the repairman moved all my files to a D drive. I feel like this should be very simple, but I can't figure out how to point LR to my D drive now and not my E drive for my library.

I read some of the previous posts on this issue. One suggested 'Just copy the catalog to the external hard drive and then double-click on it in its new location.  You might want to copy the previews as well."...is that in file explorer?

Thank in advance for your help.