How Can I Catalogue My Books?

There are a couple of ways to do this.  You can either just get an excel file and make a few columns and just add to that spreadsheet whatever books that you own or you can use a program like Bookpedia which is available for Mac at least, and maybe also PC.

This program allows you to put the ISBN number of the book into its search and brings up all the detail and adds it to your catalogue.
For insurance purposes a catalogue of your books is invaluable, especially when most insurers will not replace your books, the collection needs to be insured separately, which is a pain in the bottom.

However, it is useful to know the replacement value of your collection and you may have spent the last many years building your collection from many places on many topics and having a handy catalogue allows you to attain their worth but also see what you might like to browse.