I say it "WAH-nya".And "uaine" is the word for green in Scots Gaelic (as a general color, while "gorm" (literally "blue") is used for dark green and "glas" (literally "grey") for light green).
In Irish Gaelic (at least, according to what I learned), "glas" means a natural green and "uaine" is used for artificial things (clothing, etc.) This seems to be an oversimplification.