To add a new Category, hover your mouse over the Manage button in the header menu.
A drop down list will appear.
By selecting the option "Categories", a new page will open up with a list of all your Company's Categories.
On the top right hand side of the screen you will see a green button which says "Add new Category".
Fill in 1) your category name, 2) The GL Code (optional) 3) The Account Number.
To add this Category select the "Add this Category" button.