Use a simple fill tool to add toned colour to your pictures
If you simply drag a gradient onto your document, it will cover the entire page in colour. To refine where you’re dragging it, use selection tools to create a shape before applying the gradient. Here, we’ve used the Polygonal Lasso to create a sand dune; use a desert image as a reference.
Once in the Gradient tool, you’ll have the option to select one of a few preset gradients, or create your own. Click on the bottom-left stopper; this controls the left-hand colour. A window will appear for you to pick a colour for the first half of the gradient.
Now, click on the bottom-right stopper and select a second colour. There’s a small arrow on the bottom of the gradient preview; slide this to adjust the fade of your first colour to your second. You can add as many colours as you like.
With your gradient chosen, drag from one half of your selected area to the other. This will apply it in this chosen area; you can drag it as often as you like to perfect the exact gradient.