Hello Again,
Have you worked in Canada all year (2009)? If so, you will only need to file a federal, not a state.
Also, make sure the version of TurboTax you downloaded can handle foreign income. Sometimes the software companies release different versions that can handle returns of varying complexity. It is foreign income that you will have to declare if you worked in Canada for the entire year.
Normally the software gives you a questionnaire to fill out and populates the appropriate forms automatically, so you won't have to physically fill out the 1040. You then have the option of printing and mailing the forms or filing online. If you file online, you do not need to submit supporting documentation with the return. Make sure, though that you keep the supporting documentation in case you are audited. The time you are required to keep the supporting documentation is something like 5 or 7 years.
There is normally an exemption for foreign income of up to something like $70,000 (this changes every year). This means that if you earned less than this, you will not have to pay any tax in the US. You are still required to file a return, however. Also, filing a tax return is one way to show the US that you are interested in maintaining your US citizenship if you become Canadian.
US tax laws are much more confusing than Canadian ones, but you can find a lot of information at irs.gov.