Start by tying a slip knot in the end of a skein of yarn and secure it to the corner nail on the left side of the top rail. Then carry the yarn under the nails to the right corner of the frame. This horizontal line of yarn is the first or top warp.
At the corner nail on the right, make one counter clockwise turn around the nail, carry the yarn down and under the first nail on the right side rail and head back over to the left side. This is the second horizontal line of yarn and the second warp.
Back at the left side of the loom the yarn is brought up and around the second nail on the left side rail and brought up and over the first warp. The line of yarn going straight up leads back to the skein.
The loom is now primed for weaving.
Simple or plain triangular loom weaving consists of snaking a crochet needle over and under the horizontal warps, snagging the loose line of yarn going back to the skein, pulling it down to create a loop of yarn, dragging this loop through the warps, hooking one side of the loop on the next nail down the side on which you are working, widening the loop by dragging ti to the other side letting yarn pull from the skein as you do so, and hooking the second side of the loop on the next nail down on the far side of the loom.
Reaching up through the warps to snag the loose yarn
Hooking the right side of the loop on the next nail down on the right side of the loom.
Pulling the loop forward to the other side, drawing yarn from the skein to widen the loop.
Hooking the left side of the loop on the next nail down on the left side.
Notice in the last picture that the loose end of the yarn is again going up and out of the picture. For the next weaving, the same process is repeated except this time the loop is started on the right side. Weaving is simply a matter of repeating the process of dragging loops down from one side, hooking them on a nail, widening the loop as it is dragged sideways across the warps, and hooking it on the next nail down on the opposite side.
Instead of plucking at the warps one at a time to weave the wefts through several of them at once, hook the loop , than draw it down. Make sure the weaving hook went over the warps that the previous weft pushed up and under the warps it pushed down.
Once your triangle of woven cloth is complete, remove it from the triangle loom. The ends that remain can be woven back into the edge or converted into fringe.
To create a project, simply create several triangles of woven cloth and stitch them together into various shapes as desired.
A basic shawl pattern might include triangles arranged like this.