By now, I assume that you have downloaded the package.
If you have not already done so, download the package and save a duplicate copy. I'll use the example in the /droptarget/ directory.
To create a draggable object for an element with the id folder,
you would call the following code onload.
var folder = DragObj.getInstance(document.getElementById("folder"));
The element must be positioned with relative or absolute positioning.
To constrain the drag object to a vertical or horizontal plane, pass a constraint to the
DragObj.getInstance method.
// horizontal constraint.
var folder = DragObj.getInstance(document.getElementById("folder"),
DragObj.constraints.HORZ);
// vertical constraint.
var folder = DragObj.getInstance(document.getElementById("folder"),
DragObj.constraints.VERT);
Next in this tutorial: Instance Methods, Properties, and Event Handlers