While you are on Coumadin, you'll need regular testing of your PT/INR (a measure of how readily your bloot clots) to make sure you are within the theraputic range set by your doctor. The frequency of testing could ran from daily to monthly, depending on how stable your INR is.
You should receive instructions from your doctor about diet and medication interactions with the Coumadin. Make sure your doctor knows about any medication you take, including over the counter medications, vitamins and supplements.
Be careful about physical injuries while on Coumadin, as you will bleed much more easily.
You're lucky this was caught before you ended up with a clot in the lungs. I can tell you from experience, this is no fun whatsoever.