how do I upgrade to high sierra 10.13.0

10.13.0 is not available, it's the 10.13.6 that is available & should work for what you want...

https://support.apple.com/kb/sp765?locale=en_US

https://itunes.apple.com/app/macos-high-sierra/id1246284741?mt=12

Check to see if your iMac is compatible. If so, follow the instructions.

How to upgrade to macOS High Sierra - Apple Support

need operating system version 10.13.0 for my Mac Book Pro in order to successfully instal new Version of Microsoft Word & Excel, home office use??

Thx, Margo