The answers to your questions are contained in each post with the announcement of a new contest (new topic).
For example, you can look at the last topic, but its term has already ended. I started summing up the results. After that, there will be a separate post and a new topic will be announced. Accordingly, the rules and requirements will be clarified.
https://steemit.com/hive-185836/@bambuka/photo-contest-post-processing-15
I will be glad to see you among the participants.