How do I.....

How do I fill in an entire area with one color, like a paint bucket on ms paint and thinks like that.

er...the paint bucket. :p

But seriously, memorize these shortcuts:

ALT+BACKSPACE = fill with foreground color
CTRL+BACKSPACE = fill with background color

To fill a space, select it with the different marquees and such.
If you want to fill a whole layer, you won't need to select anything.

Oh, and RTFM!!!! :D

Where is the button?

And I Looooooove your sig.

on your keyboard.

try pressing F1 a couple of times too!

Once again, I say: "Start Here." Read the whole thing.