Whenever you visit any foreign country, you need a reason for visit. For Canada, you need reason like whether you are going for US Visa interview, or visit family friends or just for fun as tourist. For US visa stamping you need appointment letter with US consulate For visiting family or friends, you need invitation letter from family/friends For just visiting as tourist for fun, you need hotel reservation and trip plan. It should not be hard to get Canadian visa if you are in USA with valid visa. Good luck.