"post an ad" is correct and can be used in written English.
For example, you could write, "If you're looking for a new job, try posting an ad on a job search website."
And yet, when Maud sees him post an ad for a live-in housemaid, something draws her to him.
I could post an ad — 'Slave for Rent, Three Years' Payment Required.' But an ad costs money and time.
The method is easier, seductively so, almost like an A.T.M. — post an ad, and your phone rings seconds later.
For example, we can post an ad that will only show to people between the age of 24 to 40 who like art".
Lion is mean, and the other animals are too scared to stand up to him — Zebra brings a note from his mother — so they post an ad: "We need someone to make Lion stop bullying us.
Following complaints and threats of legal action, Craigslist recently hired monitors to review listings and began charging $10 to post an ad in its adult section (most of the site is free).
And as any victim of adultery obsesses over "the other" in her partner's life, I became increasingly obsessed with the casual encounters world of Craigslist, so much so that I decided to post an ad of my own.
Ms. Wertz writes that she started reading Missed Connections not because she wanted to post an ad herself (oh yeah?) but because she was "intrigued" by the idea of "a subculture of people who feel they missed something great because they didn't have the courage to speak up".
