You may want to simply unscrew your old shower head and screw your new shower head right onto your existing shower pipe, not a problem. Or, you may want to raise your shower head up 8 inches or 10 inches by replacing your old shower pipe with a new brass "S" Riser Pipe. Comes with an escutcheon. Standard 12" pipe thread on both ends. Perfect for the heaviest shower heads.
Please note: you must have a minimum of 12" (14" with the 10" Riser) of clearance in a full circle around your water outlet in order to install an "S" riser pipe.