[Zope] newbie question: level of security

hi, i guess such a question is asked before but i could not find anything in mailing list archives ( may be i used improper keywords). i would like to assign new users ( their roles are project1, project2) who have access to only those project1 and project2 folders. those project folders are located under one of members' folder. i guess it should be done thru defining local roles . but i could not do anything. can i have some advices... thanks in advance fatih