These should keep you busy learning/practicing for a while! It takes time but is worth going through all of these to see which ones are the best fit for you.:)
As you need more, or are just curious for other self help options, you can always look through our Resource Guide 1st post, main page.
S.C.
Self Help sites with breathing/relaxation exercises instructions
Panic attack relief exercises:
http://www.healthcentral.com/anxiety/c/73076/34334/breathing-lessons/
http://www.healthyplace.com/
http://www.stress-relief-exercises.com/
http://www.ehow.com/video_4405003_breathing-exercises-panic-attacks.html
http://www.psybersquare.com/anxiety/panic_relax_I
Health Anxiety - A Self Help Guide:
http://www.nhs.uk/conditions/hypochondria/pages/introduction.aspx
Helping health Anxiety
http://www.cci.health.wa.gov.au/resources/infopax.cfm?Info_id=53
Health Anxiety- The Super Scanner
http://www.get.gg/docs/SuperScanner.pdf