So, on XFCE you have a panel system. To customize the panel you can either go through “Settings Manager” » Panel. Or righ-click on an empty space on the panel » Panel » Panel Preferences
I’m not sure I understand exactly the configuration you want but you should be able to do it. XFCE is pretty flexible on this. I’ll detail here some of the things you can do.
Having Mutiple Planels
At the top of the Panel Preferences there is a drop-down menu with the panels. If you only have one you can click on the + icon to add another one.
Adding items to a Panel
In this case if I understood correctly you wanted to move just the task bar to the bottom of the screen. On this other panel we’ll add the “notifications area” (XFCE lingo for task bar, I think) by going into the “items” tab on our second panel and ckicking the + button there and adding the “notificaitons area”. If it’s greyed out it’s because only one instance of that can exist so you need to remove it from the other panel.
Moving a panel anywhere on the screen
By un-ticking the “Lock panel” on the “display” tab, some little draggable dots with show up on the left side of the panel. You click these and drag the panel wherever you want.
You can also use this to move the entire default panel to the bottom (like windows).
After you’re done, don’t forget to “lock panel” again so those drag-able dots go away.
Anyways, I hope this helps.