There are several ways to do this. The easiest is with the Smart Brush Tool, the one with the gears.
In the drop-down, select Color, then a color. Tick "Inverse" at the top on the tool's option bar
Paint over your grandaughter and the flowers, and the background should have the new color
TIP: Use the bracket keys next to the letter p on the keyboard to ] increase, or [ to decrease the cursor size. You must make a complete selection of the foreground - note the "marching ants".
It might be more interesting to have a non-solid background:
- Select the subject.
- Add a blank layer.
- Set the Foreground/Background colors to a dark and light shade of your desired color.
- Run the Clouds filter. Optionally rerun the filter (Ctrl-F) to get subtle changes in the cloud pattern.
- Add a Layer Mask and fill the selection with black to reveal the subject.
- If necessary refine the result by painting on the mask with black to reveal more of the subject, or with white to reveal more of the new background.
If you want to change the background color but retain the clouds effect, apply a Hue/Saturation adjustment to the layer:
I should have stated that I am a complete beginner. None of your
statements mean a thing to me--like "Select the subject". Select it how?
Or "Add a blank layer". How do I do that? I think I need to find a
beginner's tutorial on the Internet.
However, thanks for you input.