So what does our subject look like when we're going to do a two-point drawing? In this type of perspective, we are viewing the object or scene so that we are looking at one corner, with two sets of parallel lines are moving away from us. Remember that every set of parallel lines has its own vanishing point. To keep it simple, two-point, as the name implies, uses two - each pair of horizontals (the top and bottom edge of a building, box or wall) will diminish towards the left or right vanishing point, while the remaining set of parallel lines, the verticals, are still straight up-and-down (we only worry about those when we're doing three-point perspective!).
It sounds a bit confusing, but you don't need to be able to explain it - just understand how it should look, and by following the steps, you'll find it surprisingly easy to draw. Just remember: the verticals stay straight up and down, while we 'vanish' the left and right sides towards a vanishing point.