What do I do when the flowers drop off?

[Pollyanna]

Hi! I have never owned an orchid before and I really have no idea what I'm doing! I was given a Phalaenopsis orchid as a gift a couple of months ago and now all the flowers have dropped off it. I've read conflicting and confusing articles about cutting the spike or not cutting it. If it is best to cut it back, how far along the spike do I cut and what do I use? Any advice would be greatly appreciated. :thank you I've attached a photo to make things easier.