Nowadays, there is a need to use technology to effect citizen participation in society. Users are no longer only passive software consumers and a growing share of them are using technology as a medium to express new ideas and opportunities. In a democratic future scenario, the more people can manifest themselves through the effective and efficient use of technology, the lower the risk that those who can do it determine what others will do. However, the process of teaching and learning computational thinking, which is the basic skill for self-expression through software, is a big challenge. Teachers need to learn computational concepts themselves before they can teach them to students. In elementary and high school they generally do not have support for teaching this kind of content. This thesis presents a model for the design of active documentation which aims at supporting the teaching and learning of computational thinking. The model is based on Semiotic Engineering theory and its instantiation in a real scenario came about as an active document used in several empirical studies during three years with elementary and high schools in the metropolitan region of Rio de Janeiro. Technically and scientifically, the main contribution of this thesis is an epistemic tool for structure analyses and decisions during the design of metacommunication of active documents to support the teaching and learning of self-expression through software.