please help to change date type

[cyberweb]

hi,
i want to change pligg date type from default to persian calendar type, i mean persian date system
so i have my source code to exchange date system but i'm a new pligg user and dont know how can i change date system
i attached my source (persian date system) and can any body help me to change date type please?
i really need to change date type and if any body can help me to use pligg, i will translate pligg to persian language and send it for admin
regards