Hi @hExPY Marvyn,
Have a look at this thread https://community.openhab.org/t/template-widget-tutorial-examples-make-your-own-widget/ which explains the concept of a template widget. This is a specific implementation of this sort of widget.
The first post should then make more sense. If you are still having problems can you explain what you are struggling with so I can provide some more specific help.
Regards, Andrew