Go to your local hardware or home improvement store and buy pipe insulation. It wraps right around the pipe and is easy to use!
I skipped the wrapping and put closed cell foam tubes on my pipes, the foam was slit by the manufacturer on one side, supper simple to put on.
In addition to the insulation, depending on just how cold, you may also want to add electric heat tape wrapped around over the insulation, and keep the tap furthest from the water intake at a slow steady drip into a clean bucket so its not wasted.
Don't forget to open the doors below the kitchen sink to warm up the pipes running into the kitchen. We also used plexiglass sheets and an enclosed oil heater, to create a tent-like structure in the garage exactly where the water comes into the house to keep the pipe warm. This is only done when temps dip below 20 for several days in a row.