Hello Grendizer and welcome to the ArtRage forums 
Here are two posts I made about the Fill Tool some time ago.
Though the fill tool hasn't really changed much since I made these posts, it dose now have a 'Gap Tolerance' setting and a 'Slow Motion' setting when working with solid colours but basically the info in the posts still applies.
Basic Fills. If you are filling line art, I generally prefer having my fill colours on a separate layer below the line art layer: https://forums.artrage.com/showthrea...014#post453014
Gradient and Pattern Fills Video: https://www.youtube.com/watch?v=FDO_...ature=youtu.be
And more extensive info about about the Fill Tool can be found here: https://www.artrage.com/manuals/digi...ols/fill-tool/
Maker Of Replica Macoys
Techie Stuff:
ArtRage 6.1.1 ~ 15" Macbook Pro ~ macOS 10.14.6 ~ 4 Core i7 3.1GHz CPU ~ 16GB RAM ~ Wacom Intuos4 M