A quick and simple way to move tabs around and organize them in your collections is just to drag and drop them! Drag and tab to the collection you'd like it to belong to. Its that simple.
Now you can simply drag tabs around collections. Hover over the tab you'd like to move, drag it over top of the collection you'd like it to belong to, and drop it! Easy as that. Note: Make sure you have "tab preview" enabled in you properties to be able to view and drag tabs around.
If you're inside a collection, you can also right click on a tab → click "Move Tab" → and select the new location you'd like it to move to.