Larry, basically you start with the Select colours to enhance icon.
When it is depressed, you click the image with the largest spread of the colour you want to alter.
Holding down the left button turns that colour chequered so you can move the blob around until you reach peak coverage and release.

You can then tweak this a bit by clicking the dropdown arrow to the right of the icon and twiddle Tolerance and Fade.

The finale is selecting the Photo hue icon, picking an approximate new colour and finally sliding the Strength control around.

Acorn