How to import content from other place via RSS？

I can see the link in ths sidebar after I sybdicated the rss feed ~

but my question is how to use RSS to show the article when the ass source have new content ?

Do I need to do some thing like writing an article and do some setting for thaht writing or I can just leave those rss link in my sidebar and hope they wull auto POst the updating content ~

Sorry first if the question sounds stupid