How to make this calendar work in WP

Hi all. I’m really new to WP (and PHP in general), coming from a very limited html and ASP.net background.

I’m trying to get this calendar (or actually a heavily modified version) to work in WP. The files for it can be found here.

How would I do this? Do I create a plugin? I tried to make one, but I, as I said, I’m really unfamiliar with the process. When I activated it, it overrode the dashboard completely and I had to delete it manually via ftp.

A little more on what I’m trying to do, ultimately:
I want to use this calendar as a base for a different lunar calendar, very similar to the traditional Hebrew calendar. It will have different month names, slightly different dates, and different holidays. All of this I can do. If instead of modifying this calendar, someone has a better idea, perhaps even an easily modifiable calendar that could be changed through options in the dashboard, that would also be acceptable.

Any help would be greatly appreciated.