Change color

[Brutus11111]

I installed ALE yesterday. I was using Syntastic before. I'm very new to this.

I installed the plugin in Vim and that seemed to work out of the box so far. So all good there. I've been going through the manual (ale.txt) but it's a bit confusing for me. I don't understand some of the terminology used.

Only Issue I have right now is:

I can't really see the text that's added behind the line. I mean, it's there, but it's the same text color and background so it doesn't stand out. Right now, the biggest clue that there's something wrong is that the line number changes to a W.

Can I change the background color of the error? I'd like it to be red with white or black text. Or black on yellow. Something that pops.