The upper table is where you can select which Class, Level and Book you wish to be displayed in the spells tables below. The Feat table on the right will list Metamagic feats which can be stacked on spells, but this is not yet available. All spellcasters start with a Known Spells spellbook - in this book are all the spells the caster knows. Wizards can put an unlimited number of spells in their Known Spells book, whereas Sorcerers and the like can only put a defined number (defined by their KNOWN: tag in the class file). Spellcasters which can memorize spells can type in a name in the Book Named field. By clicking on the Add button they add that book name to the list in the Book selection above it. By clicking on the Del button you can delete the book named in the Book selection. If the Known Spells book is selected, the Available (bottom left) table lists all the available spells to be known for that class of that level. Any spells which the character knows of that level will then be displayed in the Selected (bottom right) table - each spell can only be known once so putting them in more than once will not work. Some classes (mostly Divine) know all spells automatically so the Selected table will match the Available table. Only spellcasters which memorize spells can choose a book other than Known Spells, and if a different book is selected the Available table lists all known spells and the Selected table lists all memorized spells for this book. In this case you can memorize spells more than once. Typical uses of this are for creating a book named "Underground" to hold which spells you'll memorize when in a dungeon-crawl, or a book named "In Town" to indicate which spells you'll memorize when in a town adventure.