You can check the processing times online search for Canada Visa processing times.
How to apply: again search on the internet
You will need to write a Letter of Invitation Address that to the Visa officer and explain why you are inviting your parents, mention the itinerary and strong ties to the home country i.e. why will they go back at the end of the stay, how are they going to support themselves when here. Mention in brief about your self like how long you have been here your status, etc.