You do not enter your child's earned income from wages reported on a W-2 on your tax return.
Your child is not required to file a tax return if their earned income reported on a W-2 was less than $6,300. If your child's W-2, for 2016 had federal income tax withheld, they may want to file a federal income tax return to get money back (refund). TurboTax Online has a Free version they may be able to use.
If your child chooses to complete an income tax return, it is important that they choose the following options:
Someone else can claim me as a dependent on their tax return and
And this person will claim me on their 2016 tax return.