I have an itunes account in the US and I want to buy " A place to call home" tv series soundtrack which is available in Canada how do I go about buying that albumn

To be able to buy it from the Canadian store you will need to be in Canada with a Canadian billing address on your account - you need to be in a country to use its store.

You can try requesting that it be added to the US store, but unless the record company/US rights-holder agrees to it then Apple won't be able to sell it there : http://www.apple.com/feedback/itunes.html

Is it available on other music purchase download sites that you have access to ?