How do I file for taxes on a rental property in a foreign country? I have been taxed there already

[taxmodern]

If you're a US citizen, then your worldwide income is taxable on your US tax return.  But you can generally use the Foreign Tax Credit to get a credit for the foreign taxes you paid.

Foreign rentals still go on your Schedule E.  They are depreciated over 30 years instead of 27.5 (assuming it's not a short-term rental).  You may have a requirement to file a form 8858, and there are other requirements if you have a foreign bank account.