Twitter is looking to attract small business advertisers.

The microblogging service today announced that it has launched its first self-service ad format, called Promoted Products, which will enable marketers to buy and target ads on their own. Until today all of Twitter’s ad formats required marketers to work with a member of Twitter’s sales team.

“Whether it’s an independent bookstore or an online jewelry retailer, small businesses will soon be able to easily build a larger base of engaged followers by promoting their accounts,” wrote Twitter in a blog post. “They can also feature promotions and messages more prominently in their customers’ Twitter timelines, and find new customers by promoting Tweets.”

Promoted Products enables a marketer to pay to target a consumer with a Twitter message, or tweet. The messages appear like any other tweet in a consumer’s Timeline, the first page he sees upon logging on to Twitter.com. A note below the message highlights that it is sponsored.

The offering brings Twitter advertising closer to Facebook’s ads program that features some ad formats that marketers can buy and target on their own, while others require an advertiser to work with a salesperson.

Initially only U.S.-based American Express cardholders and merchants who accept American Express cards can buy ads on Twitter. As part of a promotion highlighting the ads, American Express will give the first 10,000 ad buyers a $100 credit to place ads on promoted tweets and accounts. All merchants will be able to buy ads later this year, says Twitter.