Help! How to cast off into back of stitch

Hi

I have learnt how to cast off but my pattern is telling me to cast off knit wise working into the back of each stitch ? Please help

Knit the sts through the back loop:


and then bind off in the usual way by lifting the first stitch worked onto the right needle over the second stitch.
The pattern seems to be looking for a tighter edge and twisting the knit sts should do that.