If you really, really want to use the bucket fill tool then take a look at part 21 of my tutorial series:
viewtopic.php?f=6&t=11981Of course the fact that I don't introduce that tool until part 21 should suggest that it's not really the best way to add colour to an Inkscape drawing. As Ragnar said, it might be the Fill & Stroke dialog you're after - covered in parts 4 & 5 of my series (but in that case you may as well start at the prequel, or part 1, to make sure you haven't missed anything vital).