Although many shows advertise themselves and accept postal entries, the easiest way is to set up an account with the main organisations for processing entries. You'll also find schedules and show details on their website: note that show details and entries will be unique to one of these organisations, so you need to check regularly on each of them for up to date information about specific shows. Judges are expected to submit critiques for all Championship and Open shows: these cover the top 2 dogs in each class and allow the judge to explain good / less good points about individual dogs and the overall entry.