If possible, see if you are eligible for the form 2555-EZ and exclude the income. Note, if you are a US citizen or US resident alien, the filing requirement was around $9350 and you can't NOT count the foreign income unless you file and CAN exclude it.
See IRS publication 54 to see what to write at the top of the late tax returns.
EDIT, FILE NOW. Unless and until you file and can prove you can exclude the income, it's not excluded. If you can't exclude it, you OWE.