If you find a particular aspect to be problematic or intimidating, post here with a question or two with details and someone will have an answer. It helps (may be a requirement) to have a project in mind when attempting to learn a new program. The above-referenced programs take different approaches to creating models. Tinkercad, Meshmixer and OpenSCAD are object primitive type programs, while OnShape and Fusion 360 are sketch-based programs. Blender does both types of generation.