As you can tell, they go in alphabetical order. Starting with the first letter and then they go to the second letter. The first hurricane of next year will have "A" as the letter. The next letter of the name will come after "na" from Ana. I don't know what the next name on the list is, but AMY could be a logical name for the reasons I just gave.
There is a list of all the possible names somewhere and they go in alphabetical order using the above rules.
I hope that makes sense.