Correct, if you are considered a resident alien, then you should complete form W-4 and give it to your employer in order to get withholding taken from your wages. If you're wondering how to complete this form, don't worry. TurboTax has a special withholding calculator that you can use to help you claim the correct allowances and so on, so you do not over or under withhold. Once you've completed the questions, you can download the form.
Here is the link to the calculator.
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