What kind of attorney do I look for to answer questions regarding a Canadian marrying an American in the United States?

I'm not sure what your question is, but it sounds like you need to speak with an immigration attorney. No law forbids a Canadian national and citizen from marrying an American in the U.S., but your question is probably more geared towarded having the Canadian remain in the U.S. after she is married. That question is one of immigration law.