1) Connect the instrument output to tje input of direct box (DI) with a short instrument cable. On the DI there is a thru (parallel) output adjacent to the input jack. Connect this jack to the input of the onstage amp or powered speaker.
2) Connect a balanced (XLR) cable from the output of the DI to the appropriate input on the snake or stage box.
3) If 60hz hum is present, most direct boxes have a ground lift switch that can be engaged to eliminate it..