the eraser isn't white because your background color isn't white. If you're working on one layer, and you want the erase to erase the color and show the checkered background indicating transparency, you have to add an alpha channel. But, if you want it to be white, you should set the background color to white. The easiest way, though is to color on a different layer than the regular white. That way when you erase, the white on the layer behind shows through =)
to change the color, you click on the little color box, and go to the color you want (im assuming you've gotten that far.) when you have the color, you have to click the OK button at the bottom right hand corner of the window. if you don't the color won't change.
if you want, i can post pics, if ur still confuzed =)
