To introduce the one chick to the one hen, you could start by letting them live next to each other, with wire mesh between them. That way they can see and hear each other, but cannot hurt each other.
Then let them be together when you can supervise them.
Then, if they seem fine, let them stay together all the time.
The whole process might take several weeks, but it will depend on how your specific chickens act. Some hens are much nicer than others when you try to introduce chicks.
Make sure they both have appropriate temperatures.
You don't want the hen too hot, but the chick might still need a source of heat.
Heat guidelines for chicks:
--first week, one spot 90 degrees fahrenheit (32 celsius), plus a cooler area (preferably below 80f/ 26c).
--each week, reduce the warm spot by about 5 degrees f (2 or 3 degrees c)
--eventually, the "warm" spot is the same as the rest of the area, and the chicks no longer need extra heat. This happens sooner in hot climates, later in cold climates.