Building permit for backyard office, what’s the process?

I figure to ask here. I asked the office for Harris a few years ago and hoa and got nowhere. Hoa sent me a copy of some 6×6 shed for tools. I am in the Humble, TX area. I would like to build a backyard office since I work from home. I want to get serious with this project. Does anyone know the proper process to get this started? permits, dimensions, electrical hook ups, etc.