Classifications consist of 6 levels ( 5 for Juniors ) which are 3rd Class, 2nd Class, 1st Class, Bowman, Master Bowman and Grand Master Bowman.
To Achieve one of the above classifications you must shoot three rounds in the same season and submit scores to your records officer. For master bowman and grand master bowmen the rounds must be shot at record status shoots.
Each classification has a score required in specific rounds and this will also depend on what type of bow you are using, your gender and also age group.
The following link to Ely Archers shows an excellent set of tables where you are able to see the various categories and work out what classification you have achieved depending on what type of round you have shot.