A screen of what? My complete inability to perform even the simplest task?

I think I got it though, but there must be an easier way. I not only had to highlight the coast/waterways, but then had to fill-in the water areas with the same color as the coast, so that the bucket wouldn't fill those areas in with white as well. seems overly complicated just to remove a coastal outline, but it worked.

Anyone with any other tricks I should know about, please, feel free. Also would love if people pointed me in the direction of some non-hand-drawn mountain tutorials - I'm trying-out jwbjerk's tutorial for creating realistic (satellite-looking) mountains ATM. I love the way hand-drawn mountains look - very 'classic fantasy map' - but I can't get my tablet working and the mouse isn't really precise enough.