If the property is going to be used only on a particular page, it is referred to as “Local” and is located on that page under the “Custom properties” header.
If the property is going to be used on the entire store, then it is called “Global” and is located in the “Variables” section (see page’s Editor toolbar) under “Custom Variables” header.
To add a Local custom property open a particular page, then click the [Edit] button on the Editor toolbar.
Click the [New Property] button. Input the Name of a new property, and select its type.
To add a Global custom property, click the button [Variables] at the Editor toolbar.
Click the button [Define New Variable] on the page toolbar.
Input the Name of a new property, and then select its type.