Follow this tutorial if you want to learn how to change the eye color of an image using adobe photoshop. This process will be the same for all versions of photoshop. Its a simple process, the tutorial is made for beginners easy to follow and to recreate my results.
Do a search on goggle for Jessica Alba or what ever person you want. Or if you want to follow along with me. Right click below and copy the image and paste (Ctrl+V) think its (Command-V) for Macs it into Photoshop.
With your image pasted into photoshop, Press Ctrl+J to duplicate the image. You always want to do your editing on a copy try not to edit the master copy.
Click on the Elliptical Marquee Tool using the setting
Using the Elliptical Marquee Tool, draw a circle around the eye as shown below.
Subtract from the top of the circle to get the effect below.
With the eye still selected click on Image > Adjustments > Hue/Saturations
After doing that you will get the options shown below.
Click on Colorize and play around with the Hue and Saturation. I Usually leave the Lightness at 0.
Play around with the setting and you will get any eye color you want.