How can I draft a legal notice for unauthorized property use?

I need assistance in drafting and sending a legal notice to an advertising agency that has installed an advertising board on my vacant land without my permission. The land is jointly mutated in my name and my uncle’s name. My uncle has made an agreement with the advertising agency, allowing them to install the board and has been receiving money annually through this agreement. Could you please guide me on the necessary steps and legal grounds for this action, and help me draft the notice to effectively address the unauthorized use of my property?