To Open Embedded Webpage within 📝Topia, open the 📝Asset Editor and click the 'Links' tab. Add your link into the middle field labeled 'Use a hyperlink to open an embedded webpage'.
If this link can be opened in an iframe, it will. If it cannot, it will ask if you want to open it in another tab. If the latter happens and the former is desired, try removing the http:// at the beginning.