This first video is a GREAT look at proper breathing technique from SwimTherapy in the UK (  Check it out to help you breath properly. 

To get real speed and power, you need to master the under water catch.  This is, however, the most difficult part of the swim stroke to change and master.  SwimTherapy discuss it in the second video.

I also like this set of videos from Karlyn Pipes-Neilsen, a coach out of Hawaii.  In these videos, she is using a Versa ergometer (land-based swimming machine).  I know triathletes are all about 'getting the gear', but this is not something you need. 

I agree and disagree with the last statement she makes in the last video about rotation.  She says not to over-rotate - true.  Instead, she suggests that you learn to stretch forward and create rotation that way - also true.  However, she says that swimming flat on a Versa will help you - I disagree.  For a new swimmer, it would only create a bad habit (which I'd be happy to help you break). 

I am also a big fan of 'Mr. Smooth' from the site  This is an animated swimmer with perfect stroke technique that you can use to compare to your technique (which I'll video for you) and make corrections.