Cut off all of the long extended shoots and use them for cuttings. They root really easily and it will be worth the effort, and the cut back will cause the tree to ramify better. The tree should be placed in a larger container to grow out some and placed where it gets more exposure to the sun. The more sun the tighter and more compact the foliage will become.
As the tree is now it is too young and willowy to make a good bonsai. Give it a couple of years. This will give it time to develop out and you the opportunity to obtain a bit more experienced vision to make this tree useful.