Apple uses a scripting language called AppleScript
Go to Applications/Utilities to find both the Script Editor and the VoiceOver Utility
In the VoiceOver Utility, select "Allow VoiceOver to be controlled by AppleScript"
Now go to your home folder>Library>Scripts>VoiceOver and place the script files in here.
Note: You can right click the script to open with the script editor.
Now, open Sysytem Preferences>Accessibility and find Dictation
Select "Enable the dictation keyword phrase" and type in the name of your computer.
Then click the dictation commands button.
Select "Enable advanced commands"
Click the + button
Here you'll enter the command you want to say (title of the script you downloaded), while using any application (unless its application specific), and for "perform" select "open finder item" then navigate to where you saved the scripts and select the one that fits the command. Then click Done.
More information can be found at https://developer.apple.com/library/archive/documentation/AppleScript/Conceptual/AppleScriptX/AppleScriptX.html