How do you file taxes if you have worked under the table for two years?

You should seek out the assistance of an experienced, licensed (CPA/EA) tax preparer

who has done returns for nonfilers such as yourself.

You are probably entitled to deductions which could greatly reduce the tax you owe on the money you have been making under the table. You may even be entitled to a refund! ---- Its an "Honor System". You do not need a W2 or 1099 to report your income, CASH is taxable too :) You need to organize your income by source and you're entitled for expenses as related to the income generated. Lastly, if you can not pay the tax owed, you can settle your tax debt based on your financial situation.