How to set user permission for delete post on Public folder, and Create Public Calendar (Exchange 2010 , Outlook2007)

Hi guy.

1.I see error message. when i try create "new folder (Calendar item)" oncompany public share error message as below "

 Can't Create the Folder. You do not have permission to create a sub foleder under this folder. To check your permission for the folder, ........ 

2.How to set user(A) permission for delete post on Public folder(Company Public)

Any help for solved ?

Thanks for Advance