I have a view that lists all users webform submissions.
I want to be able to have the view show the name of the user instead of his id and display only his own webform submissions.
The solution was to specify as Filter criteria "webform submission:user " and in fields I added the same criteria. Then I customized it by creating a label name.
The video tutorial Drupal Views Module: Creating lists of content on your Drupal site really helped me discovering Views and find an answer to my question (I recommend it for every beginners like me).