It's easy. Just count carefully and comment the number you fall under. only original comments count, comment under those comments don't count. Also after you make a comment you have to wait for 3 other comment before trying another number.
Pob delegations are given to comments 11, 21, 31, 41, 51.
Alright dear, thanks for the guidance... Lemme join in as well 😊
Just drop a comment on the main post and you are included. The only problem is I think all the prizes are counted up.