How to Fetch Rss Feeds From Other Websites

I’ve 3-4 Blogs 2 on same topics
I want if i post on 1st blog
then 2nd blog can fetch feeds automatically and save that in database as a post

or Can anyone tell me how smashing network work
when someone post in his blog smashing fetch feeds and excerpt and show it in smashing network and when user click on that post he/she redirect to original blog post.