As above, literaly fill the bottle up, it will take a while to fill up the system, once its stopped going down fill it to the maximum mark, then start the car, and allow it to run up to temperature (u can flick the blowers on if u want, put them on low though, as it all affects warm up time), top the coolant up as/when it starts to go down, i personally get the cap on just before the fan is about to cut in as otherwise the expansion bottle usually overflows because its so close to boiling point, but it should be as simple as that. Once the fan has turned back off all the hoses should be good and hot, likewise so should the heaters.