Map-making question

[StarBurst]

Ok this might be a dumb question. But I have Gimp, I put it on greyscale, 513 x 513, but..how do i pick colours to paint the heightmap with?
This is what my screen looks like

there's no option to pick colours at the edge like there should be.

[wolfsquad]

I also have GIMP.
When you have your grayscale and the 513 x 513, there should be a tab called "Windows". There is an option called "New Toolbox". Open it.
There's options to change the color, paint brush/pencil and size, smudge objects, blur objects, bucket, spray paint and size, etc.

Image:

[Redlinelies]

Gimp uses a toolbox as a separate windows, 1 for workspace 1 for tools, tab key should open it I believe otherwise it's usually under preferences or view tab on windows, but as you're running the mac version Tab might open it?

Do make sure you also have the correct image preferences when saving the image if it's your first time as it will otherwise crash your map upon loading the heightmap.

[StarBurst]

Thanks guys, that was super helpful!

[wolfsquad]

You're welcome.
For the mask part, there's plenty of map-making tutorials on Youtube and here.