Impossible to create a new backlog

Hello,

I am in a very stupid situation. I created an account a couple of month ago to have access to a backlog of an employee of mine. He shared his backlog with me and all was fine. Today, I wanted to create a backlog for myself and was surprised not to be able to do so. I have only my employee's backlogs on my dashboards and no button 'create' or equivalent. What did I do wrong?

Thx in advance for your help

Kind regards