In this paper we focus our attention on the use of social software as educational enablers for use in formal online education contexts. To this end we study the hypothesis that users have to acquire a set of important Personal Knowledge Management (PKM) skills. Such PKM skills are presented in the paper. They are also examined in relation to current 2.0 technologies that can sustain PKM skills acquisition and development. However, the acquisition of PKM skills is not in itself sufficient to guarantee the online learner who uses social software the chance to be part of the relevant and effective online learning experience unless it is coupled with a proper Instructional Design (ID) Model. We therefore present a possible Instructional Design Model for the Connectivist environment. Finally, we illustrate a sample scenario in which the use of social software is implemented on the basis of the ID model presented so as to support PKM skills acquisition.