Chickens are either large fowl (sometimes called standard) or bantam. Each of these is then divided into divisions (ABA terminology; APA calls them classes, which is confusing, as class is also used for age/gender. Bantam divisions are
1) Old English/American Game
2) Modern Game
3) Single Comb Clean Legged (SCCL)
4) Rose Comb Clean Legged (RCCL)
5) All Other Comb Clean Legged (AOCCL)
6) Feather Legged
There are only two breeds in the OEGB/American Game Division: Old English Game Bantams and American Game Bantams. There are only Modern Game Bantams in the Modern Game division. The other divisions all have multiple breeds. Note that except for games, the breeds are divided by clean leg vs featherleg, and the clean leg breeds are divided by comb type. For a couple of breeds, there are more than one type of comb allowed, and therefore the birds are listed in the division that matches their comb type: for example, single combed leghorns and RIR are in SCCL, but rose combed leghorns and RIR are is RCCL.
Each breed is then divided by variety (colour/colour pattern). Depending on how your entry form is filled out, you may or may not list that the variety is AOV for the breed. For example, our county fair ONLY accepted online entries, and there were number codes for the specific breed & variety combination. Not all recognised varieties, or even breeds were available codes, and there were AOV and AOB (any other breed) codes for each division.
If you are filling out a form freehand, and do not have to use codes to specify breed and/or variety, list the specific variety, even if it is not a recognised variety for the breed. You can put "(AOV)" afterwords if you wish. The judge SHOULD know whether a variety listed is AOV for the breed or not.
The age/gender terms you will need to select from are Cock, Hen, Cockerel, Pullet, Young Trio, Old Trio. You need to look at your instructions, as some shows list birds born before a date as being Cock or Hen, but in general, Cocks, Hens and Old Trios are all at least a year old, and Cockerels, Pullets and Young Trios are less than a year old. Birds less than 6 months old will not compete well; generally older is better, as long as it does not exceed the age limitation for cockerel/pullet. If you have waterfowl, they are referred to as Old Male, Young Male or Old Female, Young Female, Old Trio, Young Trio. Age rules for waterfowl will be the same as for Landfowl (which also includes turkeys).
For the seramas, name their colour as closely as possible; I do realize that the names for serama colours are very much non-standard.