I work in photoshop and I have been for quite some time. It is the best program for editing pictures, I have tried others, but they don’t get me the same result as PS. I could be wrong but I think not 🙂
Anyway, the purple sky. It is actually really simple, open the picture (ctrl+O), then create a fill layer. The fill layer should be the colour you want to shine through. It can also be a gradient, it’s up to you.
Now you have 2 layers. Double click the top layer and the blend menu pops up. The layer you click will always blend with the layer underneath. Locate the drop down menu called “blend mode,” it is set to normal, but has a lot of options, try them out and see what they can do.
You can also set the blend mode from the layers window. If you want to, you can put the fill layer underneath the picture and try blending, that will give you different results. I had the picture on top. Now you can try the usual adjustments brightness/contrast, hue/saturation and so on, to see if they add something to the picture. If not, just save your work and get on with your day 🙂