List a yard sale online at Craigslist.org or YardSaleSearch.com. Sign up for a free account to get started, and then place a free ad by following the site's step-by-step process.
To list a yard sale online at Craigslist.org, click on your city or the city nearest you on the main page, and then type "yard sale" in the search box at the top left of the next page. A drop-down box appears showing the sections where people are listing yard sales in your area. Select the section where you want to list your ad, and then at the top right of the next page click on Post. The site guides you through the necessary steps to list the ad. Within limits, Craiglist allows placing the same ad in different sections and in different cities.
At YardSaleSearch.com, click on the Post A Yard Sale tab near the top of the main page, and then type the street address, city, state and ZIP code in the boxes on the next page. Type the details of the yard sale in the boxes provided for things such as a description, the start time and the date. The site then guides you through the steps to place your online ad.