Toriel Is In her room Sleeping.So I will Do this For now.

Here is Your Eye to start with.Choose any Color! But Only 1 color!
Im gonna use The Color purple For now Cause I see purple as an Animu Color.

Mark where your Iris will be. Draw the curve in the middle! Because that is where your Iris is, Right?

Fill the whole Orb With the Color You picked.

Select The Whole Orb using The magic Wand.I Recommend You using paint tool sai or Medibang to Paint.They Have magic Wands.Fill The whole iris with a Darker Color, Shade The Top of The Iris too!

The wand is used to select an item.The item you selected will be the only item for you to draw on.

Darken The iris Using a darker color shading Below the iris.

Use a darker color to shade the Iris.

Use a Lighter Color To color The top side corners.I used a Layer So that The color wont Fill the Top Shade of the iris.

Then a Lighter color, I used another layer to do the same thing for the other shade.

Use a shiny Light color to Color Below.

Then another shiny color.

Then another Shiny color.But Color It Smaller and rounder.

Using the Blur tool, Blur the Dark shade Below the iris.

Then Blur The light colors.

Deselect.

Using the Color White, Make a round Bubble on the top right Side of the eye.or is it Top left side of the eye? IDK.

Draw A long Line Halfway across the iris. IDK. It just looks cool.but anyways You are done with your eye! Well done! Hope you enjoyed!