It's an organizer that attaches to the long arm machine. Or rather, it is hooked to the runners.
Want to know how? Easy. Three things (or four depending on how you add it up): the organizer, the glue and 2 window hangers
Hook the rods in place--don't panic, it's not attached to the long arm--and make sure they are straight. Put some dots of glue along the top of the rods (about every inch or so is what I did). Wait the recommended amount of time (two minutes for the E6000) and then carefully place the plastic organizer on the rods.
I can move the organizer over to the machine if necessary. I glued the rods so they can't be adjusted because it would drive me crazy if they slide open, but that's a choice you have to make. If you need to be able to lengthen or shorten the rods, put your glue on the outside rod only and they will be able to adjust.
This Ikea organizer is really huge so I have room for all manner of tools and things. Notice the pliers? I'll tell you what they are for in a later post.