the snow foam helps lift off dirt, if the weather stays like this you can foam the car,wash off foam and prob dry as your car, as it would be mainly dusty, if it's really grubby then you would need to wash,alt you can use the foam if the car is very dirty to help wash and reduce risk of swirls as big bits of crap are hopefuly removed
last touch is used in your case as a drying aid so the car wont streak dry, if it is very light dirt u can use this to wipe over, as Rich says but anything more and you will get swirls