To back up TRLitsey, and to expand on what he said:
If you're new to ACAD Electrical (aka ACADE), then I highly recommend that you DO NOT try to edit the catalog info directly, without using the tools provided by ACADE. As Litsey said, there are some rules. Essentially, there is a very strict hierarchy to follow as far as how tables and things are named. If everything isn't exactly perfect, ACADE won't be able to use the info. It could even break the catalog.
Also, the catalogs are either Microsoft Access (.mdb) or SQL (.sql). In order to get information into them from Excel, you would have some hoops to jump through. ACADE doesn't have those hoops, so you'd have to do it externally, which as stated is very-not-recommended.
In order to do it through Access, you would need to be very proficient with that software, and more proficient with ACADE than you probably are now.
Therefore, understand that ACADE supplies an interface for catalog editing. Litsey showed you the two easiest ways to get to the catalog info. This is how you should do it. It's time consuming, but that's the workflow. Just enter the items you use one at a time, through the channels Litsey showed you. Eventually, all that stuff will get in there. Plus, along the way, you'll begin to become more familiar with the catalog and all of its pitfalls.
Hope this helps,
Jim

Jim Seefeldt
Electrical Engineering Technician