http://www.howtorow.com/how-to-row/elements-of-rowing-technique
This is my favourite site for learning how to row. This page not only breaks down the stroke for you but also links to videos to show you exactly how it should be done. But that is not all! There is a whole section on getting started, under the how to row/drills menu there’s a bunch on posts about different practices you can to to improve every part of the stroke. There’s a list of good workouts and even a section for sport’s scientists to learn more about rowing. All in all, an excellent resource even if you’re only ever planning on rowing on your indoor machine.
http://www.tabatatimes.com/row-better-now/
The Tabata Times is really a site about cross-fit but this is a great post about improving your rowing technique on an ergo. It goes in to detail on the whole stroke, breaking it down into it’s constituent parts: Recovery, Catch, Drive and Finish. I love the Tabata Times! The writers are real experts in their field and if you are serious about getting fit then you should read the whole site – now!
Olympic rowers train throughout the winter mostly on Concept2 machines and I can assure you their coaches are watching their technique as much indoors as out on the water. This article goes through the stroke with excellent photographs of each phase in a boat on the water. It goes into the fine coaching detail about top class rowing that other articles seem to be missing. Do you need to read this to be able to workout on the ergo? Probably not. However, if you do ever progress to a boat, I would say it essential. The articles certainly helped me put another angle on what my coach was trying to tell me, which at the time was a great help.
http://www.britishrowing.org/taking-part/indoor/training-advice
Clearly you can’t add a resource about rowing without including the britishrowing.org site. There is masses of advice here including tips on technique, information on races and how to find clubs.