You can check Kijiji for that as well, but a good landlord that follows laws won't rent a one bedroom to 3 people.
You may be able to find someone that will rent a one bedroom to 3 people, but consider if that's the type of landlord you want.
I understand it's normal in other countries for the family to share one bedroom. It's different in Canada. Don't take it personally - just cultural differences and building codes. A child is consider 0.5 a person for building codes. You're allowed 2 people per bedroom. So for you, a wife, and one baby, you have 2.5 people. You would have to have two bedrooms legally. However, you can sleep together in one bedroom. That part is fine. No one can tell you the baby must sleep in a different room.
For a nice area, expect to spend at least $1200 a month. One bedroom apartments near my house (great location, near the Circle Route buslines, #3 busline, and the C-train) is going for $1195 a month. We are also very close to several schools. Most areas of Calgary are decent - just some areas to avoid in the SE.