a bit worried that it would be difficult, but the leather needles have a little chisel shaped point on the end which hammers through the leather as it sews. i highly recommend buying these needles as well as the upholstery thread, which is much stronger than regular thread. your camera is going to be on the end of this strap, so the extra few dollars now are definitely worth it!
check that the strap and attachments combine for the correct length.
with the d ring fed through the middle of the leather piece, bunch one end of the cut scarf neatly between the two sides of the leather.
first sew closed the end 