I'm very new to Photoshop and have a little knowledge of photo editing but not much. I have been tasked by my boss to change the colour of part of an image to another but I'm not sure how to go about the task. I've been reading some of the tutorials and articles in support but I'm getting more and more confused. I could really do with some pointers please. I am trying to change the blue step to match the colour of the green steps.