I am having trouble finding titles that do not appear in the database. In particular, The HBO series Carnivale.. Is there a way to ask for titles to be added?

To expand a little on what's been said.

If you're trying to add by UPC/EAN, which is the best way of adding titles, and it's not found then that's because no user has contributed the title under that particular UPC/EAN.

As has already been said the majority of entries have the accented a, so to add by title you need to enter that into the search box.

What you can do is download one of the existing entries that is the closest match to your region/what you have and change the UPC/EAN and locality as necessary. You can change these by selecting the profile in your collection list, then go to DVD in the top menu bar and select change EAN. This will allow you to change both the locality and EAN.

You may also need to change the region, which you can do by double clicking on the profile in the collection list and deselect/select the appropriate regions.

If you want to submit you may need to edit some of the data and if you're unsure of anything then it's best to ask questions here.

Contribution rules can be found here - Rules link

There is no obligation to submit data, so if you just want it locally then that's fine. Just remember to backup regularly.