why wont my nissan micra start now a new battery has been put in?

I TRIED TO START MY NISSAN MICRA AUTOMATIC AND IT WAS TURNING OVER BUT NOT FIRING UP. SO I TOOK THE BATTERY TO HAVE IT TESTED AND ITS UNSERVICEABLE. SO I HAVE NOW BROUGHT A NEW BATTERY AND FITTED IT BUT THE CAR IS NOT STARTING AT ALL AND IS NOT FIRING UP OR TURNING OVER BUT THE LIGHTS AND RADIO ARE STILL COMING ON. I HAVE TRIED READING THE MANUAL TO SEE IF THE CAR NEEDS RE-PROGRAMING OR SOMETHING BUT ITS NOT TELLING ME ANYTHING. ITS FUSTRATING BECAUSE THE CAR WAS TRYING TO START WITH THE OLD BATTERY IN AND NOW WITH THE NEW BATTERY NOTHING. PLEASE CAN SOMEBODY HELP ME