This is sashay yarn as it is sold in a ball.
It is easiest to work with if you unravel it and wind it around a paper towel roll tube. You can see the netted texture of the yarn.
Tie a knot in the end to keep it from unraveling. This gets hidden in the first couple of ruffles, so don't worry about it. You can trim close to the knot if strings hang down.
Hook goes through the first loop, in from the front picking up the top string space.
Skip a space and loop through the front to back to pick up a second stitch.
Repeat until you have 9 or 11 stitches for your first set.
The 9th or 11th stitch gets held and pulled through all the other loops so you end with a single stitch on the hook.
Here it is--the single stitch.
I like my scarf sections tight so I begin on the closest space, skip a space and then add 8 or 10 loops so you always pull the last through and leave a single loop on the hook.
The ruffle starts to form right away!
Here is a completed scarf created using 9 loops for the first set and 8 for each subsequent section. Make as long/short as you like. Most people like these to loop around the neck at least once.
Once scarf is at desired length, cut yarn and knot like at the start. Continue looping every other space until you come to the knot. Once at the knot loop the final section over the knot to secure.