Adding a Tint to PNG image in Flexslider with Wordpress

I am new to StackOverFlow (new to programming in general); I find myself in a stump regarding adding a tint to the image of the FlexSlider on front page. (which currently just have one post) I have looked at some related posts - taking some suggestions into consideration - to no avail. Could someone please assist with a suitable css code to add a tint (light brown) to my FlexSlider image?

site: curlyafrodotcom WP: 4.1.1 (current version) Theme: Dazzling (current version)

Thanks in advance, Candace