You can register yourself using a name (given its available and acceptable, meaning no close match found in the search - mind you each search cost you some money), or a BN (Business Number). If you need this done quickly to not loose the opportunity of the job, get someone to do it quickly, depending where you live it could cost starting $500. One thing you must keep in mind is that once you register, you have to file corporate tax annually (based on the registration date of your business) even if you don't make a penny in the business, or you have to close the Business to avoid filing tax. This is separate from your personal income tax. Now there are different kind of registration, and you can get a lot of information by simple Google search. Get some advice if its worth registering, like if the contract is for couple of month etc. Its its not suitable check with employer if they would hire you directly probably on a lower pay rate. Best thing if you have no time, consult with some local Tax accountant or your own if you have one and does this kind of work (which most ppl do).
Good Luck, and congratulation.