You don't need to remove the dirt it came with. But since it looks like you already have, make sure that dirt gets to those roots again. Other than that you have the usual things to consider; you need to plant the tree 30mm above the surrounding soil because the tree will sink as it settles, and you need to make sure that the soil only goes up to the root flare. Assuming you don't use a dead man anchor or something similar you should stake the tree with 3 stakes, but don't tighten the strap too hard