How do I add panels to Pixton?

Can you explain to me, step-by-step, how one might add panels to Pixton? I'm having some difficulty navigating the platform and would appreciate a clear and concise breakdown of the process. Is there a specific menu option I need to select, or do I need to click on a particular tool to initiate the panel-adding process? Additionally, are there any limitations or restrictions I should be aware of when adding panels, such as size or quantity? Your help in clarifying this would be greatly appreciated.