Q.Orchids
What do I do with them when they stop blooming?

You can cut the dead blooms off, but don't cut all the way down to the bottom of that stem, because they usually sprout new growth somewhere along it. You'll be able to tell when the stem gets dry and brittle, trim just that section off and with proper care, you should get new growth the following season.
This article may also help you:
https://www.gardeningknowhow.com/ornamental/flowers/orchids/indoor-orchid-care.htm