Once the First Steps stage is completed you will be able to see what progress you have made in each Field. In the First Steps Stage, click the scroll on the left. This will open up all the Fields you have discovered and their progress and what level you are currently at:
As you progress through the book you will find that you will need a certain level in each Field. Once you use these they will be deducted and you will need to gain more levels. This can be done by either scanning items or using the Research Table.
There are many more Fields to discover so just keep scanning and researching.