I'm a resident alien, but it seems that I didn't enter any information from form 1042. Is there any thing wrong?

If you have already submitted your tax return, you will have to wait until the IRS either accepts or rejects your return. You cannot return to the program to make any changes before that. 

If your return got rejected for whatever reasons, you can return to the program to report the new income along with other changes.  You do not need an amendment 1040-X.

If your return has been accepted, you will have to amend your return by filing a form 1040X.  You should not try to amend your return until it has been fully processed and you have received your refund or your payment has cleared.

Beginning with the 2019 tax year, you can e-file amended tax returns. If you used TurboTax to prepare Form 1040-X, follow the software's instructions to e-file the amendment.

To see how to amend your taxes, click here: 

Steps to amend in TurboTax

Form 1042-S code 19 is compensation for teaching.  Exempt code 4 indicates your income is exempt due to the tax treaty.  To enter the amount in TurboTax online program, here are the instructions:

• Report your full income under the appropriate section. Then enter the treaty exempt amount as negative amount (e.g. -5000) under Federal Taxes / Less Common Income / Miscellaneous Income 1099A, 1099C / Other Reportable Income
• Download and fill in a Form 8833 from IRS to claim an exception.  https://www.irs.gov/pub/irs-pdf/f8833.pdf
• You cannot e-file.  You can still use the TurboTax program to prepare your amendment 1040-X, but you need to print them out and submit by mail along with the form 8833.