This chapter aims to guide users in their use of the model. Building the STICS model has always been a twofold scientific and technical challenge. The STICS conceptual scheme is built like a set of modular bricks, which means that many processes are available in the standard version and new ones can be easily added in the research branches (§ 1.5.2). These processes can be activated or deactivated as options to reproduce actual farming practices or to describe soil physics, crop development and growth processes. The first three sections deal with these options: chapter 15.1 covers the driving options, chapter 15.2 the strategy options and chapter 15.3 the formalisms. As we mentioned above, users must determine the relevant local parameters, but we do provide some tips in chapter 15.4 to help users fill in these values. In the last part of the chapter, we present a brief overview of the STICS software tools (the JavaStics interface and Stics R packages) and the STICS forum where users can get additional support and information.