You could draw a path around the person with the pen tool or lasso (depending on your photo, you may have to draw around the edge of the ocean also.) Make a selection with feather 0. The feather will control how sharp the boundary is. Feather 2 or 3 will soften the edges.

To change color it can be done several ways. Image/Adjustments/Curves or Image/Adjustments/Levels are a good ways. You could also add layers, adjustment layers or color overlays.