Inside your Handso once you unscrew the lid to insert the bar of soap you will find the silicone strap that will allow you to handle it more securely and hang it in the shower from a hook.
Here is your Handso
Open the lid by unscrewing it counterclockwise, inside you will find the strap. Pick it up and put it back next to Handso
Now grab the lanyard and pass the thinner end through the loop present on Handso, exactly as you see in the photo. If you grasp the lanyard near the end the operation will be easier.
Once the buttonhole is fed in, re-grab the lanyard on the other side and slide it to the end, as in the second photo.
There are only two steps left. Take the silicone end of the lanyard and pass it through the opposite end.
At this point you will just need to continue pulling on the silicone end. Your lanyard is now properly attached to your Handso.