How do you write Aramaic?

It depends on whether you are asking how to write the Word Aramaic with Aramaic letters, or what alphabet is utilized in the writing of the Aramaic language.

If the former; אֲרָמִית

If the latter;

Modern Aramaic is often depicted with Syriac characters, whereas Biblical and Talmudic Aramaic use Hebrew script (an adapted Assyrian alphabet) which is known as K'tav Ashurit.