For fancy effects, several gradient layers can be stacked up, using different color schemes at different angles. Adjust the transparency of each layer to control the final mix. The lowest gradient layer should ordinarily be fully opaque, but sometimes letting some of the original background show through is useful. You can add painted, slightly blurred masks to individual gradation layers so sort of dapple the light. You can also assign clipped Curves and Hue/Saturation control layers to each gradient layer, but you quickly reach a point where you lose control of the final effect.
Plenty of youtube videos about making selections. The Quick Selection Tool with Refine Mask are very powerful tools. When you are using the Quick Selection tool the "Alt" and "Shift" keys toggle between subtracting and adding bits of the selection, and the "Width" and "New Selection" buttons at screen upper left is useful too. I would guess your particular job might take no more than a couple minutes, once you know the scheme.
There are third party selection tools available with (perhaps) more capability, but I don't think you would need them for your situation.