This type of marketing is done online. It helps the site by doing methods to let it rank on the top of search engines which will mean a lot of traffic. It stands for "search engine optimisation".
There are a lot of people offering SEO services, some good, some bad. A typical small site for a town or parish council is unlikely to need to spend money on SEO. The best approach is common sense. Make your content relevant and straightforward, avoid duplication. If you can, ensure that your pages have good titles (the title that appears in the browser bar).
Although it is nice to see the council web site in search engine results, it is unlikely to bring large volumes of useful traffic!