What you need minus the wrench.
The neck twists to tighten the attachment inside. Hold the chrome button to lock it while tightening.
Insert the attachment and start to tighten.
Hold the button to lock the neck and provide resistance while twisting the neck.
After installing the attachment.
Again, sorry for the blurry photos.
By the way, make sure to do this while the Dremel tool is unplugged. It could get ugly if you accidentally turn it on during this process.
Make sure the neck is tight by using the Dremel wrench. Tighten it to the point that it's snug. Good luck with your project!