You must have "Full Access" or "Limited Access - Website" permissions to edit your site.
A "Feed Reader" is a type of page element that allows a feed from a different site, such as X, to be displayed on your website.
To add a Feed Reader:
Sign in to your site and turn on Edit Mode.
Go to the page where you want to add the feed reader and click Add Page Element.
Scroll down and choose the Feed Reader page element.
Input the settings, and click Create This Page Element.