Because I am lazy, I am going to paste in a reply I just typed out for the same question as asked by someone else:
To add a credit, first search his name in the database to see if there
are others using the same name. If so, use his name and a Roman numeral
one higher than the highest in use. If not, just use his name as he gets
credited on screen. Then, go to the page for the title he's been
credited in and add his name to the cast/crew. If he did not already
have a page, one gets created automatically if/when the credit is
verified and accepted. This takes 1-14 days. If it doesn't appear, add a
screen capture of his name appearing in the credits (or, better yet, if
you have it now, upload it to a pic hosting site and provide a link in
the explanation field you'll see or you can upload it here then add the
submission number here and staff can forward it to the page editor for
you.
See:
How do I add myself/my credits to IMDb?
Adding Data to IMDb
These links all appear when you click the "help" link on any page of the site.
Please excuse the "he's" instead of "she" or "you" as it was a third party asking about an actor.
