Moving to the US from Canada?

Alright, so my fiancee and I have been together for 3 and a half years. Now as nice as it would to be to just waltz on down into the US I know it it MUCH more complicated than that. What I need to know is what exactly am I going to need to do. I havn't been able to find any information, maybe you guys can give me links to websites or just let me know what I have to do? I would REALLY appreciate it.