The four (main) parties in Canada are:
Liberals
Conservatives
New Democratic Party (and if you need to know where they stand on the political spectrum, consider that they evolved out of the Canadian Communist Party)
Bloc Quebecois
Now, the Bloc are not a national party, but only contest in ridings in the Province of Quebec. Their main platform is the separation of Quebec from Canada -- and they hate Liberals.
Really, the Liberals and the NDP are left-wing, the Conservatives and the Bloc right. Don't try comparing to Republicans and Democrats, though
I am a Conservative, but that doesn't mean I like their leader, Stephen Harper. Conservativism is about maintaining the status quo, which is why I'll likely end up voting Liberal.