Using the Dodge Tool in Photoshop
The Dodge Tool is often unheard of when it comes to Photoshop. What this tool does is it lightens your image. This is mainly used to define images with highlights and shadows.
With your image open on Photoshop, select the Dodge Tool in the tool bar on the left hand side. It looks like a purely dark gray lollipop.
With the tool selected, you can change the brush size to make it bigger or smaller, along with the exposure, which is how strong the stroke will be when used. The higher the exposure setting, the more of an effect you will see on your image. With your preferences selected, you can now begin to click and drag the tool on your image wherever you want the effect to be placed. Effects can be changed back by simply clicking Edit> Undo.