how do i upgrade from MAC OS 10.13.6 to 10.4

Hello V2Tim,

This article guides you through how to update your Mac's operating system: Update macOS on Mac - Apple Support. Follow this guidance:

"Use Software Update

Before following these steps, it's a good idea to back up your Mac.

1. From the Apple menu  in the corner of your screen, choose System Settings or System Preferences.

• If you chose System Settings, click General on the left side of the window. Then click Software Update on the right.
• If you chose System Preferences, click Software Update in the window.

2. Software Update then checks for new software. 

• If Software Update finds new software, click the button to install it. The button might be named Update Now, Upgrade Now, Install Now, or Restart Now, for example. You might then be asked to enter your administrator password.
• If Software Update says that your Mac is up to date, then no new software is currently available for your Mac model. Software Update shows only software that is compatible with your Mac.

 If you don't see Software Update

• If you don't see an item named Software Update, choose View > Software Update from the menu bar in System Settings or System Preferences. Or use Search in the corner of the window to search for Software Update.
• If your older Mac doesn't include Software Update, open the App Store app instead. It's in your Applications folder. Then click the Updates tab in the App Store to check for updates. You can also search for software by name."

If you run into an issue, make sure to check this additional support article: If an error occurred while updating or installing macOS - Apple Support.

We hope this helps. Let us know if we can assist with anything else at all. Take care.

10.4 is not an upgrade to 10.13.6.

10.14 is an upgrade to 10.13.6.