You can extend Worpress’s functionality by using plugins, which are add-ons created by other developers that add new features. For example, a plug-in might add a new widget to your sidebar to display Twitter or Facebook posts, or let you add a Poll or event calendar.
There are a number of useful plugins pre-installed on your blog, you can see the selection under the Plugins menu.
Plugins need to be activated before you can use them, so go to installed plugins under the Plugins menu, and click the “activate” link beneath the description of your new plugin.
Some plugins will need to be configured through an options page. Some plug-ins will add another option under the Plugins menu, while some will add another menu item to your admin sidebar. Some older plugins will have a “settings” page that you can access from the list of installed plugins.
Try not to activate more plugins than you need, because they can slow your blog down and create problems.
When things go wrong with your website, it might be a good idea to deactivate some plugins to see if they were causing the problems.