You will want to check with your travel agent and find out if your airfare was booked through the cruise line or independently. If it was booked through the cruise line then you are all set. Since you are coming from Idaho, you are probably flying on the day before your cruise departs or else taking a night flight. (I don't think you could make it from Idaho to Florida in time on the day your cruise departs.)
If you are booked through the cruise line, a cruise line representative will meet you in the baggage claim area of the airport and tell you where to go and what to do. (On the off chance that a cruise line representative is not at the baggage claim when you arrive, there is usually an information desk in the baggage claim area and they can tell you where to meet your cruise represenetative.) If arriving the night before your cruise, the cruise line will put you up in a hotel and then get you to the ship the next day. They will also return you to the airport at the end of your cruise.
If you are using airfare booked independently, then you are responsible for your accomadations and transportation. (To find out about the hotels near the airport, use Tripadvisor.com.) If I am not mistaken, Carnival Liberty departs from Ft. Lauderdale. If you fly into Ft. Lauderdale, it is pretty reasonable to take a taxi from the airport to the port. If you fly into Miami, you are probably better off finding the Carnival representative and purchasing transfers on the Carnival bus.