An aim of the proposed information systems theory (IST) is to build a bridge between the general systems theory's formalism and the world of information and information technologies, dealing with transformation of information as a common non-material substance, whose models in forms of computer algorithms and programs could be implemented to different material objects, including a human's thoughts and languages. A new approach to IST is based on a single concept and follows mathematical formalism that uses an information variation principle to build an information systemic model of a specific object. The problem's solution, procedure and methodology modelling are illustrated by the application of the information macrodynamics (IMD), which reveals the system model's main layers: microlevel stochastics, macrolevel dynamics, hierarchical dynamic network (IN) of information structures, its minimal logic, and optimal code of communication language, generated by the IN hierarchy, dynamics and geometry. The system's complex dynamics originate information geometry and evolution with the functional information mechanisms of ordering, cooperation, mutation, stability, diversity, adaptation, self-organization, the double spiral's genetics, the system's generation, decaying, and transferring information to other systems along with the information mechanisms of heredity and replication. The developed IMD's theoretical computer-based methodology and software have been applied to such areas as technology, communications, computer science, intelligent processes, biology, economy, management, and other non-physical and physical subjects with their mutual interactions, informational superimposition, and the information transferred between interactions.