Hi Lucy.
You can use ever with the verb ‘to have’, as it shows in your exercises. The best friend I ever had. Etc. However, it doesn’t sound right with other verbs, unless it’s a question. Have you ever been to Paris? Yes, I have been to Paris. It’s fine to add ‘ever’ in the question here, but it’s not needed for the answer, as you’ve either been to Paris or you haven’t. You could add extra detail here to your answer by saying things like ‘once’, ‘a long time ago’, ‘recently’ etc.
Have you ever been to Paris? (The question means did you visit Paris at any time of your life). Yes, I have been to Paris, but only once and a long time ago as a child.