Leads and bights
Each type of Turk’s head knot is classified according to the number of leads and bights and method of construction. The number of bights is the number of crossings it makes as it goes around the circumference of the cylinder. The number of leads is the number of strands around the circumference of the cylinder, before doubling, tripling, etc. Depending on the number of leads and bights, a Turk’s head may be tied using a single strand or multiple strands. Mathematically, the number of strands is the greatest common divisor of the number of leads and the number of bights; the knot may be tied with a single strand if and only if the two numbers are coprime. For example, 3 lead × 5 bight (3×5), or 5 lead × 7 bight (5×7).
There are three groupings of Turk’s head knots.
1) Narrow, where the number of leads is two or more less than the number of bights (3×5, or 3×7),
2) Wide, where the number of leads is two or more greater than the number of bights (5×3, or 16×7), and
3) Square, where there is a difference of at most one between leads and bights (7×8 or 8×7).
The number of bights determines the shape found at the center. Three bights create a triangular shape, while four create a square. A two lead, three bight Turk’s head is an overhand knot.
A two lead, three bight Turk’s head is a trefoil knot. (2,n) alternating torus knots are (2,n) Turk’s head knots.[3] ((p,q) = q times around a circle in the interior of the torus, and p times around its axis of rotational symmetry)
Source: http://en.wikipedia.org/wiki/Turks_head_knot
Make your own turks head gridmaker
paracordguild.com have come with tutorial to make turks head knot. More information here: http://www.paracordguild.com/tie-turks-head-knot/
Many YouTube tutorials: Mabel Marble
knottool.com has a collection of videos of how to tie turks head. Text from your side: The following is a series of short videos that show how to tie a 6 Lead by 7 Bight Turks Head on the Turks Head Tool. The videos introduce the Turks Head Tool, the Turks Head Cookbook recipe format and some basic methods that may be used in the tying of turks head knots.
http://www.knottool.com/