On the left is a table listing the stats, the unadjusted scores, any racial modifiers, and the resulting total. There is a column of plus and minus buttons – by clicking on a plus button you may increase the stat in that row by one, and by clicking on the minus button you may decrease the stat. If you're in Purchase Mode (see the Options tab above) you cannot decrease stats below 8. If you're not in Purchase Mode then you must decrease stats to put points in your pool before using those points to raise other stats. In the lower left-hand corner is the Pool which indicates how many points you have to spend. If you're in Purchase Mode it will indicate the cost of the character in parentheses. The Roll button will randomly generate the stats via the 4d6-drop-the-lowest method, or set them all to 8 if you're in Purchase Mode.
On the right is a table of Races and information regarding each of them. As with all tables in PCGen you can sort it by clicking on the column header and reverse the sorting by holding down the shift-key while clicking on the column header. As you click on a race your character's race will be set to that selection, and the racial stat modifiers will be reflected in the stats table on the left. Any initial benefits from a race (like a Human's initial feat) will only be granted if the character has that class when advancing to first level. If you later change races you will not gain that feat retroactively.
At the bottom of the window is the Alignment list box. If you're in Star Wars Mode (see the Options tab above) this will be hidden from view.