With great respect, I think steve_oc is off by one definition (except that he is also right to say descend now and pick an angle to the best place - good words). Looking for a good place to land is "land as soon as possible", "land immediately" is land in the place that is between your shoes in the chin window (bravo 73 had it right). I wrote these words into the flight manuals for at least two currently flying models, so I think I know that the words are intended to mean.
Land Immediately generally means be quite ready to ditch, or even put it in the trees below. In some models the RFM guidence is to descend to a low altitude, reduce speed to minimize power and then fly toward a safe landing area. If any further degradation takes place, land now right below. In such a case, land immediately means: "Not for the faint of heart. You are going to hit the ground very soon, do you want to be the pilot, or just an occupant? If you want to be the pilot, pick a place to control the landing. If you want to be an occupant, pussyfoot around looking for a nice place and risk having the machine make your decision for you."
Airplanes make the decision easier, because any off airport landing is a crissis. As Bob Hoover put it: "If you're faced with a forced landing, fly the thing as far into the crash as possible."