The link for the tutorial seems to be broken
They've deleted the thread it seems. Ah well. I thought I'd try something a little 'simpler' for my first recolour, though I may have been overambitious. Something that requires much less change would be better, I think. I recoloured the coleus plant, and this is what I came up with:
I don't know what the plant is called that has the white and green leaves, but that was what I was aiming for.
First I tried adding the file to the save file for the house itself, but it wouldn't work like that. I haven't tried adding things to my world file yet. Hopefully that has more success. To get this one to work, primarily so that I could see my handiwork ingame, I made it as an individual package and put it in my overrides folder (as a mod). Fingers crossed I can get it to work as a non-mod later on!