its work automatically you have to give time range, like after 3 hours, 6 hours, or after every 24 hours etc
WP-o-Matic makes autoblogging a snap by automatically creating posts from the RSS/Atom feeds you choose, which are organized into campaigns. So basically its automatic and may I ask what's with this that you ask about its automatic function? Do you experience an issues with it?
I wouldn't recommend you to use wp-o-matic because it works with WP database directly, so once upon a time you will find your blog dead (db crashed). I'd recommend you to try the another FREEWARE WP plugin called CyberSyn Plugin. Some features: CyberSyn doesn’t use big and slow 3rd-party GPL libraries like SimplePie or MagpieRSS. It parses the RSS feeds for those XML tags only that can be imported into WordPress posts and ignores everything else. So it has rather compact and extremely fast code! Advanced RSS parsing algorithm has an ability to pull the feeds fully automatically. Furthermore, you can assign the updating period to each particular feed. Also you can set up a maximum number of posts that will be syndicated from the feed at once. This is a very useful feature for SE optimization of your blogs, because search engines don’t like blogs that add 100 or more posts at once. Adjustable post uniqueness identification by GUID, post name or both. CyberSyn has no problem with syndicating various embedded media content such as tube videos etc.
The plugin has not been updated for a long time so i would suggest to use the WordPress built in function.