I am having problem in installing joomla 1.5 in plesk panel?

If i set 777 through ftp also, it were returning to normal value. my server IT department said that i can do from my plesk control panel itself.. i do not know how to give permission in that.. there were two options like iis user and iis wp user.. what are defalut setting that i have to check before i am installing joomla in plesk and what are the folders i have to give permission and how.. please tell me and do help.. i had installed now with problem bcoz of it now i could install template or any package directly through my admin
please help in this problem to fix.. i were in big headache, my service side they were not helping bcoz of i am using third party package, they were saying like this itself..

 

Hello,
i have successfully installed joomla in my plesk control panel. I have given read write permission to my ftp user and enabled ftp.

i was able to install extensions.

but now i don't know why my support server team have disabled write permission to my ftp user.

now again suffering from the problem.


Harlin