Page data type can be created like Global data type, but data items addition mechanism is different.

There are 2 ways to create it.
First:
Go to Data/Page Data type
Right-click on it and choose "Add Datatype"
Create your data type (similar to global data types)
If you right-click on newly created page_data_type "Add data" is not accessible.
Go to Content and select page that you need to add data to.
Right-click on the selected page and choose "Add Datafolder"
Choose you page data type from the list and add it.
Now your page has attached data type.
Data items can be add to it - choose "Add data" option.

Second:
Another way to create page data type is following:
Go to Content and select page that you need to add data to.
Right-click on the selected page and choose "Add Datafolder"
Choose "Create new type from the list of options"
Create your data type (similar to global data types)
This data type will be added to your page.
Data items can be add to it - choose "Add data" option.

To use page data type in Content area Visual function has to be created.
Go to Functions/Visual functions and add new visual function.
Select your page data type from the list.
Select appropriate template on Visual settings tab
Switch to Visual Layout tab
Right-click on Content area and select necessary field, by choosing Insert=>Field
Result can be previewed on Preview tab.

As you visual function is ready it can be inserted into Content area of the page as any other function.