A series like „Nos voisins les pirates“ can neither be found in its French original title nor in English or German. I would like to add titles as heavy user like it‘s possible in Goodreads.
On the desktop version of the site, every page has a Menu button at the top. On the bottom of that menu is the Help Center. https://help.imdb.com/imdb Typing "how add title" into that search box yielded this, among others: Adding a new title
But make sure the title(s) are really not already in the database by looking at the filmography of the principals. I especially like to use the Collaborative search to find titles shared by pairs of principals. That is found under the Advanced Search link in the dropdown menu:
bderoes, Champion