Presumably, you're talking about a SmartDialog, and the logical paging mechanism inherent to SmartObjects. If this is the case, then you can read the 'CurrentPage' property value. To get the value, use the getCurrentPage() function that's already provided.
Incidentally, a really good way to find out which properties are defined is as follows. Chances are, there's a 'get' function for most listed properties that you can use to get the value. The name of the function is (almost) always 'get' + 'PropertyName'.
Make sure the ProTools menu is visible, then run your procedure. Click the 'Procedures' icon (the icon with 4 little squares) to start the Procedure Object Viewer. Highlight your procedure (if you've run from AppBuilder, it will have a '.ab' extension). Click the 'SmartInfo' button, then click 'Properties'. Now you can see a list of all defined properties and their values.
You can also use the Procedure Object Viewer to see whether there's a 'get' function by looking in the 'Internal Entries' list.
