Dyeing wool shorts?

I have no idea how to dye ANYTHING..... but I just bought a pair of luxe wool shorts on the TP, and I want to dye them (well, when they get here... :LOL). They are currently light blue, and I REALLY want them to be a bluish PURPLE... dark or light, it doesn't matter. I figured that since the pants are already blue, it shouldn't be too hard to get them purple.

So.... how do I do it, where do I get the dye, what should I know, etc?? TIA!