My cactus is turning a reddish color.
Your cactus could be turning a reddish color because it is getting exposed to too much direct sun. If this is the case, I wold move it to a location where it gets filtered sunlight. Your cactus may also be changing color because it is dehydrated and not getting enough water.
How do you take care of it. And where should I put it
Good news! You are within their native growing zone, and they will flourish outdoors, in your area.
These are epiphytic, residing in the crotch of a tree, or in cracks in rocks. Planting them will need to mimic that.