I have mostly finished the Christmas Tree I was knitting based off the "Patriotic Decoration" on the KK website.
The basic instructions are to e wrap the loom 3 times and knit 1 over 2. After knitting the amount of rows called for, do a gather finish to remove the stitches from the loom, leaving a 1/2" hole in the middle for the dowel. Using the loops from your cast on, gather the bottom as well leaving a 1/2" hold in the middle as well. It will form a disc.
This is the size of the discs on my tree
Blue Loom: 15 rows, 21 rows
Red Loom: 24 rows, 30 rows
Green Loom: 27 rows, 30 rows
To finish, you slide the rows through a 1/2" dowel cut to size (I have to find my saw to do this). I have not decided how to top my tree off yet. I may make a plastic canvas star. You can decorate it anyway you want. I chose to use gold Glitterspun yarn. You could also use beads.