Even if you donate to the library, they are not obligated to add them to the collection. If a number of your books are pre-ISBN that pretty well guarantees they will not. They need contemporary books people want to read. Unless they are a university or archival library, they are not interested in keeping old stuff. They'll just booksale the stuff they don't want.
librarything.com is a pretty easy way to get your books cataloged. I use it for my collection of over 2,000 books. Calaloging is not just a matter of finding a Dewy number and sticking it on there. MARC (Machine Readable Catalog) is a very intensive and complex method of tagging everything from size to subjects. The neat thing about librarything is that once you get your books in there, with as minimal effort as possible, you can downlad a comma delimited file of the full record to import into any system you want. Cataloging is intensive and time consuming so you want someone else to do the bulk of the work. Don't underestimate the amount of work involved here.
If you REALLY want a serious library automation system there are a couple of open source systems out there: Koha.org is one and Evergreen (open-ils.org) is another. These are real and complex systems with OPAC (Online Public Access Catalog), check-in/out, etc. I wouldn't do this unless you were really hard core.
Google home library software and you will find a ton of stuff.
P.S. I worked in the library automation field for about 30 years as one of the first "systems librarians."