Start off by clicking "edit", then "find."  Type in the text string lnz for the baby you want to hex based on the code you're using:
 
ab.lnz Asian Boy:  short hair, bald/dots, curly, sparse.  
abx.lnz Asian Boy:  full hair, 1 curl, 1 strand, mohawk.
ag.lnz Asian Girl:  two Ponies, bald/dots.
agx.lnz Asian Girl:  one and three ponies, mohawk, 1 curl.
bb.lnz Black Boy:  short hair, bald/dots, curly, sparse.
bbx.lnz Black Boy:  full hair, 1 curl, 1 strand, mohawk.  
bgx.lnz Black Girl:  one and three ponies, mohawk, 1 curl.
bg.lnz Black Girl:  two Ponies, bald/dots.
brb.lnz Tan Boy:  short hair, bald/dots, curly, sparse.
brbx.lnz Tan Boy:  full hair, 1 curl, 1 strand, mohawk.
brg.lnz Tan Girl:  two Ponies, bald/dots.
brgx.lnz Tan Girl:  one and three ponies, mohawk, 1 curl.
wb.lnz White Boy:  short hair, bald/dots, curly, sparse.
wbx.lnz White Boy:  full hair, 1 curl, 1 strand, mohawk.
wg.lnz White Girl:  two Ponies, bald/dots.
wgx.lnz White Girl:  one and three ponies, mohawk, 1 curl.
This is the begining of a white girl's lnz.
Where it says eyelid color, the number 48 is the color of the eyelids.  You can change this color to anything you want by typing the new number right over it.  If it is a one digit number, like 2, then type 2 and then space.  If it is three digits, it is ok to type over the first dot.
Scroll down quite a ways and you will find the Outline Color Override section.  This is where you can change the babyz eye color.
Now you're going to have to make sure you have a babyz code to create the baby you want.  If the code you are using will become a baby with blue eyes, then change all of the 109's and 110's.  For a pretty shade of light blue, leave the 109's and make the 110's 109 as well.  For Grey eyes, change all of the 14's.  If the baby will have Lt green eyes, then change all of the 149's and change the 134's if the baby will have Dk green eyes.  If the baby will have brown eyes, it gets more complex.  For Lt brown, change any 17's, 12's and 204's... because they have 3 shades for light brown, and you don't know which you'll get.  For Dk Brown, just change any 16's.  Use the color chart to pick the new eye color for your baby.  Be away that not all colors come out exactly as they appear in the color chart.  Not sure why, but I've sometimes found they turn out brighter or darker than I expected.  Your best bet is trial and error.  Some colors look great with some babyz, and others don't.  Sometimes it seems hair color effects the way the eye color turns out.  If the color doesn't turn out how you want, then you can always choose not to adopt the baby, and go back to the babyrez file to try another shade.  Hope this was helpful for you!