KAppTemplate is an application to start development quickly using existing templates providing basic repeatedly written code and a proper structure.
KAppTemplate picks up templates which are installed on your machine. Those are often part of the development files for libraries or can be downloaded e.g. from the website store.kde.org.
Answer the wizard questions on each page and generate your template.
README file in each template will allow you to find out how to build the template. It will also give you links for tutorials related to the project. After the project is generated, KAppTemplate's job is finished and you are on your own to build it.