Here are the steps to display RSS feed in your Joomla! site:
1. Go to extensions>>Module Manager
2. Find the Feed Display module
3. Enter the URL of the feed.
4. Save and display the module like any other module.
However there is a second way, which is to use the News Feeds component that comes with Joomla!
1. In the administrator go to components>>News Feeds
2. In the component you can manage your news feeds and assign them to categories.
3. To show the feeds on the front end make a component link in your menu.
