Hello! So for my first tutorial I choose to do something simple. I think this will take you max. 5-10 minutes. I used a blue eye for this tutorial. I've tried this with brown and green eyes but I think it works better with blue eyes.

Step 1. Open Gimp and the picture you wish to use. Here's the link for the eye I used.

Step 2. Open a new leyer. Make sure the layer fill type is set to transparency.

Step 3. Using the paintbrush tool color WHITE the eye but not the iris. Make sure it is in the the layer you opened.

Step 4. Set the mode of the  layer you painted on to to overlay.

*If you want to have the eye look icy you can stop right here.*

Step 5. Open another layer and name it "Layer 2"

Step 6. This step is basically like step 3, but this time you have to use a dark blue. I used 080c66 but you can choose another one.

Step 7. Now once again you have to set the mode to Overlay.

And you're done! 

I hope you had no trouble following the tutorial. Please let me know what you think about my first tutorial!