RSTNL is hosting a session at the Open Science Festival on 31 August, 2023. This workshop aims to teach participants effective collaboration strategies and tools via GitHub. As a use case, the session will take the development of training material for researchers. Examples of training material used in this workshop are lessons will be taken from the Carpentries Incubator, an online database that contains many lesson development projects with a focus on teaching programming practices and coding for research. The lesson content of all Carpentries Incubator lessons is expanded and collaborated on by community participants via GitHub. By exploring different lessons that exist in the Incubator, participants will learn how to use GitHub to start and contribute to developing open source, high quality lesson material. GitHub also provides an environment for managing project tasks, communication channels for effective team coordination, and strategies for decision-making and governance within open-source projects. The skills and techniques covered in this workshop will focus on developing lesson material, and are not focused on any specific programming language or skill level. However, skills learned in this workshop are transferrable to other open-source software initiatives, fostering a culture of collaboration and improving the quality of research software in support of open science. This workshop is organised by research software training NL (RSTNL), a community of practice around teaching programming skills to researchers.