Active materials and structures offer a promising route toward adaptive and intelligent systems capable of self-shaping, morphing, or performing mechanical tasks without conventional actuation. Such systems rely on the controlled coupling between mechanical deformation and material-intrinsic actuation, which can be triggered thermally, electrically, or by embedded stimuli-responsive components. Understanding and predicting their behavior requires computational frameworks that can capture both structural mechanics and actuation processes in a consistent manner. This contribution presents an active shell finite element formulation designed for the analysis and design of flexible thin-walled structures with embedded actuation and programmable mechanical response. The method introduces an additive decomposition of strain into elastic and actuation-induced parts, enabling a unified treatment of mechanical and actuation effects. Within this framework, actuation can be prescribed for forward analyses or treated as an unknown field in inverse problems, allowing the determination of required actuation patterns to achieve a desired shape or deformation. The approach provides a versatile foundation for simulating and designing active, functionally graded structures, where geometry, material, and actuation interact in complex ways. It forms the basis for computational tools that support inverse design workflows and simulation-driven development of adaptive, programmable and morphing structures.