"To post an ad" means to create and publish a message or notice online or in a public space, usually with the intention of advertising a product, service, or event. Full definition
Employers can reach the most qualified candidates by posting an ad for an employment or internship position for marriage and family therapists. (camft.org)
Specifically, any advertiser interested in posting an ad on a heated topic like gun control or abortion will need to be verified. (bgr.com)
Get your name on a list or even post an ad in your local newspaper. (familyblawg.com)