You will need to obtain a temporary worker visa in order to legally work in the US.
As a Canadian citizen you may be eligible for TN Visa which has an initial period of stay of 3 years. The requirements for application you can take look at the CBP's site. Good news is that there doesn't seem to be a quota on the TN visa applicants.
You can also apply for an H-1B visa if you qualify but you can only do this in 2015 as H1 status is subject to quota and for 2014 it has been filled.
In general you will need to have your perspective employer submit a Petition for Nonimmigrant Worker and so on but you can review the respective sites for details and usually for employers lawyers do this kind of work.
There are other possible visas that may be available but these may be the more likely candidates.