How do you use cleansing foam after nose surgery?

I'm on day 10 after surgery, and I've been using cleansing foam. When I use it, foam gets inside my nose, right? How do you remove the foam inside your nostrils? Do you just hold your nose under water? The hospital told me not to blow my nose, so I just put my nose in the water for 2-3 seconds, but I'm wondering if this is the right way to do it.