Hello Yil and thanks for the reply.
I fact i used to create the users using gadduser and put them in GUEST group. However, when i use the user's login to check what it can see, i am able to walk all the way up to site root and see all the folders on site. I am not very familiar with ownership and making things visible/accessable to specific groups/users only. All the 1st level directories /* are owned by ioftpd/ioftpd. The /GUESTS folders ownership was set to ioftpd/GUEST as i thought that means the admin user owns this folder and all GUEST group members only may access it.
In fact it is what you mentioned that i want to achieve. If a GUEST user logs in, it must not see any other folders than /GUESTS and within /GUESTS only its own folder.
I have to play around with what you mentioned to see if i can get it and make this working for me. Guess i have to come back and ask a little more.