but how do I make it like my original Slack13 does the panel?
Not sure what the 13 panel looked like. You customize the number of panels, and many panel settings from the XFCE settings manager. Start button --> Settings --> Settings Manager --> Panel. You can have more than one panel. The + and - buttons add and subtract panels.
To move a panel, right click on the panel, the drop down has a Move function. Proporties allows more customization.