Question: How do you ask for a fee waiver as an international student?
You don't say if you're asking about a college application fee waiver or a testing fee waiver. "The Dean" is guessing it's the former, but “The Dean" likes to be thorough (at least when it doesn't require excessive effort ;) ), so I'll cover all the bases just to be sure.
If you would like a U.S. college or university to waive your application fee, your first step is to determine if this institution will grant fee waivers to non-citizens. Some do; some do not.
If you can't find this question answered on the college's admission Web site (look in the section that is specifically directed to international applicants), then write to the staff member who oversees applications for your country. You can probably find the name and contact information for this person on the Web site; if not email or telephone the admission office to ask for the name and email address. Not only will you get your question answered when you write the admissions rep who covers your country, but also you will have established a “relationship," which might prove helpful later on.
If the college DOES permit fee waiver requests from international students, ask an official at your high school (your school counselor if you have one; if not, a head of school or other administrator) to complete the form that you'll find here: http://www.nacacnet.org/studentinfo/feewaiver/Documents/ApplicationFeeWaiver.pdf
You will then submit this form in lieu of payment, and the college will notify you if your waiver request is NOT accepted.
If, however, you need a fee waiver for the SAT or ACT and you are not a U.S. citizen, you can only get one if you reside and test in the United States or United States territories.
Hope that helps. Good luck!