i have used the same method me ole mummsy has used for years with her houseplants with my mj plants with pretty good success.. simply fill a glass up with some water and place the cut end into the glass of water.. within a week or two you should have healthy roots... i like to change the water out every two days or so as well..
you'll want to mist the leaves a couple of times a day as the plant has no roots and the only way for it to get water is through it's leaves... you can also cut say the top bit of a 2 litre bottle of soda, and flip it over as a dome to keep the humidity in..
i've also seen people simply take the cutting that you have now, and place it in a container with some soil in it.. same deal as before, mist it a couple of times a day, a use something to keep the humidity in, same as before..
there are lots of other ways to skin a cat as well, but these two are old as shit and work fairly well ime..