Don't worry, it's nothing like the sticky horrible colour hair sprays they used to sell in pound shops years ago, this is much more subtle and a lot less drying on the hair. I simply spray the ends of my hair and then lightly spray a little higher up towards my face to give a gradual fade to the colour. I then brush through the area I've sprayed partly to make the hair softer (the spray leaves a slight crunch to the hair if not brushed, just like any hairspray would) and also to tone down the colour slightly. If you want to achieve real brightness, simply brush less or not at all.
It's such a quick and easy way to enjoy the trend, and after one hair wash it's completely gone - perfect!
I'm going to try purple next!