If you look at the end of the ESC, where the leads come out (both ends), is there a place with 2 or 3 small prongs sticking out? This could be where the jumper is plugged in, or it may be missing. If this idea doesn't work, I were you I would try another ESC if you can borrow one, or look for something like this:

http://www.hobbycity.com/hobbycity/s..._BEC%29___BESC

or even buy one of Nitroplanes' own ESCs like this:

http://www.nitroplanes.com/vose10abresc.html