|I have not had too much success with Hydrangea but someone just gave me another one and would like how best to grow it in a pot if possible.|
Hydrangeas are fond of east Texas conditions. Thus they like bright shade (some morning sun is okay), moist soil and some compost in the soil with mulch on the surface. In a container a standard potting mix is fine. If you can provide such conditions around the outside of your home they should do fine. If you can water with rainwater all the better as your high sodium water will tend to cause browing of the leaf edges.
Good luck with your gift plant.