In Foliobook 3.1 categories are useful but require some preplanning.
Currently it is not possible to move categories around in the structure you are creating for your portfolio.
For this reason we recommend the following process for learning and planning to use categories in a portfolio.
a) Make a backup of your portfolio before enhancing it with categories.
b) Watch both the category videos and experiment with your portfolio adding a test category or two. Add some sample content (e.g.: galleries) to these categories and practice navigation and customisation. However once you understand how this works, delete these test categories.
c) Once you understand how categories work and you have had some hands on experience, sit down with a piece of paper and sketch out how the structure of your portfolio will use them.
d) Backup your portfolio again and create the categories you need based on this design
In a future update we will make it possible to move galleries and categories around in the portfolio structure, however before this happens you need to realise that it can be quite slow to change the portfolio structure, so its worth spending a bit of time designing it before you start creating final categories and populating it with galleries.
Videos related to this topic
Categories, planning your structure
Video Tutorial : Categories Introduction
Video tutorial : Categories II