Screen sharing feature is not available in the modern version of Skype.
You're welcome. Probably Skype will add this feature in next release.
In order to use screensharing feature in Skype, please download Skype for Desktop which offers that functionality. Skype for Windows 8 doesn't support it since Windows 8 Modern Apps don't have that capability. It is a Windows 8 Store apps security feature.
The whole point of the question was in regards to windows 8, whereas your response link only allows windows 7, Vista and XP... Reading previous answers, the answer seems to be that at the moment, screen shraing is not available i am afraid a very useful function however and would like to see it incorporated in future updates