Fold the canvas in half lengthwise. Starting at the hemmed edge, mark six inches from the edge on the folded side and 20 inches from the edge on the hemmed side. Use one of your stakes as a guide and draw a diagonal line from point to point. From that bottom point, on the hemmed edge mark over 10 inches and mark 38 inches from the line on the folded edge, draw a diagonal line connecting your points. Repeat in reverse, marking 10 inches from the line on the fold and 38 inches along the hem, draw a diagonal line.
Fold the fabric over the new seam you just made so that the right sides are facing. Mark a line 2-1/2" from the sewn edge. Pin and sew down that line to create a channel for the stakes. Repeat the with all remaining panels.
Stand up the teepee and adjust the stakes until you have a nice even shape, tie the stakes together. First tie the twine around one stake, then wrap it around all of the stakes many times, and secure it all with a simple knot.