This technical briefing will enable ICSE attendees to gain hands-on experience with conducting systematic and rigorous qualitative data analysis using socio-technical grounded theory (STGT), and introduce the basics of theory development as an advanced practice in qualitative SE research. It will be useful for students and professional researchers with all levels of experience, including those attempting qualitative research for the first time and those curious about what developing a theory involves. It will equip attendees with the knowledge, skills, and resources required to handle qualitative data from human and LLM sources, and to derive rich descriptive findings, taxonomies, theoretical frameworks, models, and theories.