Caring for my Hydrangea?

I bought a Hydrangea (blue in color) potted plant about 4 days ago, I am wondering what to do with the flowers once the are wilted. Do I cut the whole thing off, or leave them be. And should they be inside or out. I live in Texas and right now it is anywhere between 65 and 80 degrees? Another thing should the blooms be wilted already?