Here is how I completed my hooked hoop. When I finally finished crocheting, (it took forever) I pulled the crochet tube onto the hoop. To close the hoop I used a 3/4th inch insert coupling, which can be found in your local hardware store, and looks like this:
You want to use the coupling size according to the size tubing you have. My tubing is 3/4 inch round. To insert the coupling, you have to warm the ends of your hoop. Some people use a hair dryer, some use boiling water, I use fire. Be careful not to burn/melt your hoop or yourself! When the hoop is warmed it makes it more pliable. You can then easily insert the coupling halfway into one side of your hoop. Then warm the other end and insert the other half into that side and close up the hoop like so:
I left a long tail on the end of my crochet work so I can use that to sew it up. I just used a whip stitch to sew the ends together.
Now I have a new colorful hoop! I need to practice my moves..