You can modify the ArcMap table of contents to suit your needs. The order of layers listed in the table of contents determines how layers are drawn on your map. The layers listed at the top will draw over those listed below them, and so on down the list. You can easily move layers around to adjust their drawing order or organize them in separate data frames. If you can't see a layer, it may be hidden by another layer or display only at a particular scale.
You can move layers in the table of contents by clicking on the layer name, dragging it up or down in the list, and dropping it in its new position. A black line indicates where the layer will be placed.
For more information, see ArcMap help.