Originally Posted by thatirishguy
Just pop the cap on the upper reservoir place a funnel in and let the car idle for a bit? Thanks again guys
Yes, that's it.
It will take 10+ minutes for the coolant level to rise enough that you don't have to hold the funnel.
Obviously when you're done, the coolant level is over the cap level, so you need to drain some out with a siphon. I usually run that siphon to the overflow tank by the driver's headlight to bring the coolant level back down to a level I can put the cap on.