Get Moodle from the official website, at http://www.moodle.org/. Go to the Download Moodle page and select the version and format that you need:
For a new installation, the Latest Stable Branch is usually your best choice. The Last build: information tells you when it was last updated with a bug-fix or patch. This is usually irrelevant to you; the version number determines which features you get, not the build time.
For a production server, do not use the standalone packages mentioned above; they are insecure. Instead, use the latest stable branch.