Duplicate Content

I have read lots of posts that say writing articles is a good way to get traffic.However I have also read that search engines frown on sites that have duplicate content.So if write a article for my site then submit it for others to use or vise verse I find a good article and use it for my site that would be considered duplicate content correct?What am I not getting here?

search engines frown on sites that have duplicate content

It's not really that they frown upon it and penalize you for it, they just don't want to fill up their databases with multiple copies of the same stuff.

If you use an article, you need to include other information on your web page so that the web page isn't a duplicate of another web page. Search engines compare web pages to other web pages to find duplicates. So, if you used an article on your site then adding commentary or a review of that article or related information to that article would make sure your web page is not a duplicate.