Pick up pear bumps

Please can anyone help? I am knitting this bottle cosy.
I have reached the part to form ridge. I don’t understand this part about "with left needle pick up pearl bump of next stitch 6 rows down etc.
Thanks in advance.

To make it easier to pick up purl bumps in a straight line when forming the ridge, thread a length of cotton embroidery floss through the purl bumps of the appropriate row first. This can easily be picked out every inch or two, as sts are picked up.

Form Ridge
Next Row [WS]: [With left needle, pick up purl bump of next st, 6 rows down, p this st tog with next st on needle] to end of row. This will form a ridge on the right side of the work.

It’s similar to this tuck in knitting.

It may be easier to use a smaller needle to pick up all the bumps 6 rows below first as in this videol