Meteor showers occur when the path of Earth's orbit takes it across the path of another object, usually a comet, that has left a debris trail behind it. For the Orionid meteor shower, that object was the famous Halley's Comet, and the meteors are caused by tiny particles of dust left behind by the comet burning up after encountering our atmosphere at a speed of over 237,000 km/h.
To see the Orionids, it's best to look for their 'radiant point', which is the part of the sky that they apparently originate from. In this case, in the hours after midnight on October 21st, find the constellation Orion in the southeast (look further to the east if you are in Western Canada), and find Orion's Belt. Then, look up and to the left from there, following Orion's right arm — which appears to be held up over his head — towards the feet of the constellation Gemini. The meteors will appear to radiate outward from a point between those two constellations.
Officially, the meteor shower is happening between October 4th and November 2nd, and meteors from this shower can be seen on any night between those dates, but the best viewing time will be this weekend, when the Orionids reach their peak. The best place to view from is somewhere out in the country, since city lights create enough light pollution to completely obscure your view of the night sky. The best time to view should be between midnight and dawn on Sunday morning, because the moon — which can also cast enough light to make viewing difficult — sets just before 11 p.m. Saturday night, and anyone watching could see around 25 meteors per hour.