The 16-20 Loop
New Spey, I lack a printer or other means to send visual material. But since this knot is so simple, perhaps it's worth a try:
Thread the tippet through the hook eye a foot or so. Bring the tippet end back up the standing line (of the tippet). A few inches from the end, make a small loop (say 1/8 - 1/4") around the standing line; clamp it there with thumb and finger.
Wrap the tippet end back down itself and the standing line, toward the fly, 2 1/2 or three turns. Pass the end through the little loop; moisten and tighten. Slide the knot down to the eye by pulling the other end of the standing line. (If done right, the knot usually makes a little click as it's seated against the eye.)