You'll need at least one candle in the color you want to change your eyes to. You also need a pentacle. You can draw a pentacle if you don't have one.
Light the candle(s) and sit in front of it/them and chant the following three or more times:
"One, two, three, eyes change for me,
One, two, three (color you have now) to (new color) I see."
Take a deep cleansing breath while you envision yourself with the new eye color, then chant this three or more times:
"By the power of three, so mote it be."
Again visualize your eyes changing from their original color to the new color, then check the mirror.
Note: This spell may only last a day or so if only using one candle. And the color of the candle will be the new eye color.