I had mine done at a garage as i had booked it in for them to look at it but the day before it stopped doing it as the weather had started to warm up. So i left the booking and had the fluid done.
To do it at home you use a turkey baster to get the old fluid out iirc. Once you replace it you then go lock to lock 3 times i think to blead it.
My fluid was the same, black and thin like petrol!