Opeds are not where you break news. It might be a week -- or three weeks -- before a newspaper publishes a piece, though it's still important to write and send opeds quickly.
There are three main types of opeds:
1) Responding to a story
Here's a common example: say you're working for a non-profit that tries to incubate small businesses. The newspaper will run stories whenever the latest unemployment figures come out, and that's the perfect setup for writing an oped.
Refer to the story (by headline and date) and talk about the real debate over how to create jobs -- some people say tax cuts, others say a better educated workforce.
Another common time for an oped is responding to a bad story or scandal that affects you.
2) Rebutting an editorial
If there's an editorial that you completely disagree with, and it's a big enough issue to warrant a long response -- not just a letter to the editor -- then call the editorial page editor and ask if you can do a rebuttal.
Make sure this type of oped focuses on the arguments in the editorial. They're not signed because they're written as a committee. Don't assume the editor or publisher wrote it, and don't attack their motives. Be respectful.
3) Rebutting another oped
If there's a fresh oped bringing up an issue, and you've got the other side, there's a chance to respond.
Just make sure there wasn't already an editorial or oped giving that other side.