I would start by getting it into a pot with some bonsai type soil. Something that will be coarse enough to encourage root development, allow air flow and maintain moisture. There are lots of different soil mix recipes out there you should be able to take one down to a garden center and find the ingredients. Then I would let the tree sit in good light with you watering it when it needs it till you see the first new leaves. While you are waiting for this to happen check out some youtube videos on Ficus and get an idea of how and when to cut.
Once the tree gets that new flush of growth and they are all dark green and healthy looking you can start working on branch choice and defoliation to increase the ramification for this tree. I would bet it would be three years for this tree to really coming into it own and look great. I already looks good and healthy so you are off to a good start.