If you use outside resources for your web needs, or have a dedicated web person or company, call them immediately. If you have a department or staff, even better. But— if you are working on your own, you would do yourself and your business a favor to contact a reputable web developer to discuss how to make your site accessible and avoid possible lawsuits. The older your website, the more likely it is that it is NOT compliant. Take action now!
The words in the tag should be more than a description. They should provide a text equivalent of the image. In other words, the tag should include the same meaningful information that other users obtain by looking at the image. In the example of the mayor’s picture, adding an “alt” tag with the words “Photograph of Mayor Jane Smith” provides a meaningful description.