How one can save the whole contents of a website on a CD/computer?

File> save page as?

Use a web crawler/archiver like Blue Crab.

On a Mac I use SiteSucker for this. You didn’t specify your operating system so I just tossed that out there. I’m sure something similar exists for Windows.

Well, there is a Windows version of Wget but the learning curve is steep.

I use HTTrack on Windows for doing this type of thing:
http://www.httrack.com

Google “site rippers.” You can’t download an entire site every time. In fact, there’s a lot of stuff you won’t be able to get at all; anything that’s dynamically rendered through Ajax, php, aspx, etc. won’t be available. Likewise, a lot of flash objects won’t download.