rss

If your theme is widget enabled, just use the RSS widget. If not, you have quite a few options that a forum search will turn up. One such option is to use a Syndication Plugin. You’ll find some at this link: https://codex.www.ads-software.com/Plugins/Syndication

Hope that gives you some ideas.

What is the RSS widget?

An article: https://fallenposters.wordpress.com/2006/08/14/wordpress-tip-rss-sidebar-widget/

my theme doesnt have a widget

[…]If not, you have quite a few options that a forum search will turn up. One such option is to use a Syndication Plugin. You’ll find some at this link: https://codex.www.ads-software.com/Plugins/Syndication