help!

Try practicing. First, start by drawing a sky with clouds. Try to use all of the tools because that's what they're there for. (I'd suggest you use the spray paint and paint brush for the clouds) then, if you are happy with it, add a sea. Keep on using the tools to make it look nice. Then, do a boat. Go on and on, and you'll have a nice scene of the sea. And you can also practice using the tools.