Been covered a million times. Have the car on an elevated driveway -not too elevated though- just to help bring the crossover up above the rest of the system a bit better. Too much will bring the radiator above the crossover and defeat the purpose.. so like i said .. not too elevated.
Circulate coolant until all air is out. bring car up to normal operating temp with cap off, when it reaches operating temp put cap on then shut off. After it cools, take cap off, start car, run to operating temp. Repeat until all air is out.
Once, it took me three sessions to get all the air out. Three days after work, driving the car to work. My radiator was a bit gunked up though, prob wouldn't have taken so long if that wasn't the case. but, it can take awhile. Do a search for more info, this has been covered a whole bunch.
..and yes you fill it in the crossover.. .