How do I add an item (product) to a category that is not on the list

Hi,

I am new to opencart, and i have a question related to adding a product and linking it with a category

How do I add a product to a different category - one that exists, but is not listed in this dropdown menu
http://shrani.si/f/H/yP/4PkYoM4f/untitled.png - picture of what i am trying to do.

Thank you and best regards

Have you tried just typing in the first few letters of the category you want it to appear in, it should then autofill for you.
Im sure there is also a mod to extend the default list from 5