2-In my opinion these are the most important steps that you have to take after landing (Ofcourse there are more, and I try to recall them and complete this answer later):
2-1- SIN card: Find the nearest "Service Canada" office by searching in internet and see what documents do you need to request a SIN number/card. The people working in Service Canada, are the most helpful and friendly persons that you may ever seen.
2-2- Health insurance: In Ontario, it is called OHIP. You are eligible to have a provincial health insurance card after 3 months stay in Ontario, but you can apply the first day.
2-3- Driving license: In Ontario, find the ministry of transportation website and the places where you can do driving test. Iranian driving licenses worth almost nothing here. You have to do all tests all over again. Make an appointment through online services for a written exam (emtehan ayeen-nameh). After you passed the exam, you will get G1 driving license. For a regular person, he/she has to drive one year with G1, while being accompanied with a full licensed driver (not alone). The Iranian license helps you to bypass this step, and if you pass the written exam, then you can make an appointment for a road test. (This is the only help that your Iranian license can do!). After passing the road test, you will be given a G2 driving license and after a while (I think 1 year) you can apply for a full license. The steps are different in other provinces. I had to mention that you need to buy a driving rules book (You can find it in all ministry of transport offices across the city) to study before your written test. Also, I suggest you hire a driving trainer for 2 to 4 hours to learn about the driving methods in Canada. Believe me, you will need that if you want to pass the road test. Something are very different and something are not. But getting some training will give you more self-confidence.