In a three-way switch there should be a powered switch (Line switch), and a Load switch. Then there are two travelers that the current switches back and forth to. The red wire must be one of the travelers. Leave it alone.
You will need a meter to figure out the rest. You didn't mention if there was a ground wire up there. If there is, then the diagnoses will be much easier.
Attach one lead to the ground, put the meter on voltage and find power. Mark that, or those wires. Flip one of the switches, recheck for power, mark the wires with power. Flip the other switch, recheck again for power. Turn the meter to ohms, check the wire that does not have power. That should give you a reading. If it does, then that is your neutral. Tie the rest of the wires , one to the light, the other two together. You may have to try a few different combinations, but you will find it.
If no ground, keep your meter on voltage. you will notice that two or three wires will have voltage then not have voltage when the switches are flipped.
It will be harder to determine neutral from a traveler without a ground.
There is no way to just identify the wires by the colors in a switch circuit. You will have to have a meter. The only other tip I have is that if there is a 2 wire coming into the box, it could be a line feeder or an extension to another light, load. If there is only the one light on that circuit, then that is most likely your feeder and your neutral is the white.
WHOA!! I just noticed that you are in Canada! You'd better get a meter before you get KILLED! Does Canada have a code?