Ever = 'at any time'; it is the opposite of never.
We generally use ever in questions.

It was the best wine I have ever tested.
Have you ever been to Paris?

Ever goes immediately before the main verb.

Never = 'at no time'

He has never visited me.
I'll never forget how kind he has been.

Never goes immediately before the main verb.

We usually use the present perfect with ever and never.