1. Open up a picture that you want to be colored ( I chose my one-year old Pitbull )
2. Duplicate the layer by holding CTRL + J - Once you have done that, click on the Gradient tool on the toolbar and press Q ( Quick Mask ) on your keyboard. Now with the Gradient tool, click and hold from the left side of the picture to the right side of the picture, a red gradient should appear like this.
3. Image -> Adjustments -> Color Balance ( Fool around with the colors here, I just chose random color levels.
4. For the second part, repeat Step 2 but with a different direction ( Instead of left to right, try up to down )
5. Trying different gradients are a good idea, if you're tired with the same gradient change them!
6. After a couple of minutes of quick masking and deleting, this is what I got
