Path options specify the relative or absolute path of either a file or a folder (depending on the option). For example, the path and name of an image file is expected with ImageName.
There are built-in variables provided that automatically resolve to paths for the Rainmeter application or individual skins. These are described at Path Variables and Skin Variables.
In addition, there is a built-in variable #@# that resolves to the @Resources folder in the root config folder of the current skin.