In JMP, change to the selection tool (under tools > selection or hit the "s" key on your keyboard). Select the item that you want to move and drag it where you want it. Depending on the size of the journal and what you have in the outline items there may be a slight lag while moving things around, but this is rare. When I'm reorganizing journals, I'll close all the outline items to make it easier to move them around and see where they are going.
You might also have a look at this webinar: Creating, Using and Sharing JMP Journals
Best,
M