Google, Microsoft and Yahoo — whose bottom lines depend on selling ads linked to search results — are pouring millions of dollars into initiatives to demystify search-based ad campaigns and help small advertisers make the leap to pay-per-click advertising.

Several drivers are at work. The U.S. search advertising market is expected to hit a record $14.4 billion this year and swell to $17 billion in 2012, according to research firm eMarketer. Microsoft and Yahoo, as search advertising partners, aim to increase their combined 30% slice, while Google intends to keep a tight grip on its 65% share, according to research firm ComScore.

Each wants to compel local businesses to purchase those sponsored links that appear alongside search query results on Google, Microsoft Bing and Yahoo Search.

“Small advertisers are critically important,” says Kevin Lee, CEO of search consultants Didit.

However, it’s all too easy for novices to become befuddled, says Larry Kim, chief technology officer at advertising consultants Word-Stream. The advertiser must bid, auction-style, for certain words and phrases related to a product or service that a consumer might type as part of a search query.

Payments are then calculated for each click on a sponsored link.

Small advertisers often waste money on poorly executed campaigns, Kim says.

So Google recently launched AdWords Express, a paid service that manages search ad campaigns for small advertisers.

It also introduced free phone support for advertisers and free help designing mobile websites and pitching products within its Google+ social network.

Microsoft is doling out incentives for consumers and advertisers to switch to Bing and AdCenter, which supports ads on Bing and Yahoo Search.

Bing users can earn credits redeemable for products, gift cards or charitable donations through the Bing Rewards loyalty program. And Microsoft has been distributing coupons worth as much as $200 in click credits to entice small advertisers to try AdCenter.

In the past month, Traci Lester, electronic marketing specialist at tech training firm ASPE, has diverted a portion of her company’s advertising budget to AdCenter.

“I’m definitely Google-biased,” says Lester. “But if you’re serious about pay-per-click advertising . . . you’d be missing a huge market if you’re not advertising on Microsoft.”