This is a tutorial for working a steek into crochet work, I’ve written the tutorial in double crochet (single crochet if you’re using US terms) but it will work in half treble and treble too.
I’ve written it so that the opening is at the beginning of you your work, but you can just easily add it in half way through, close it up again (perfect for thumbholes) or leave it open to create an opening at the end of your work.