D4u2s0t

I just ordered a fuel filter from ced, should have it in a few days. I read the how to, and it seems very straight forward. The only thing im not sure about is how to use the quick disconnect. I was looking at the picture and it just looks like a circle, and it doesn't make any mention in the how to as far as what to actually do with it. any help would be appreciated. Also, does anyone know the size of the tool i'll need?