Ok, bring the needle out of the fabric. Insert it a short distance away. Bring the needle point out again right next to where it first emerged. Do not pull the needle through the whole way, but leave it sitting in the fabric, with only the eye below the fabric. Hold the eye below the fabric with one hand, and wrap the thread around the needle with the other. Wrap enough times to span the length of the bullion stitch. To test this, lever the needle tip downwards towards the other end of the stitch to see if the quantity of wraps looks about right. When you are satisfied that you have enough wraps, gently hold the wraps on the needle with the wrapping hand. Bring the other hand up from below, and pull the needle through, keeping your wrapping hand loosely holding the wraps to keep them under control. Pull the thread through until the bullion lies flat against the fabric, and then let go of the wraps. Insert the needle at the second end of the bullion.

Does that help? In my books (“Mountmellick Embroidery: Inspired by Nature” has right-handed instructions, and “The Left-Handed Embroiderer’s Companion” has left-handed instructions) there are step-by-step instructions with diagrams that illustrate this.