Save information and retriving using shared object

i need to save some information in a shared object.
Example : User’s id , address and telephone.
I also need to do a login , using the user id as verification, in order to retrieve the datas stored in a shared object.
Can anyone tell me how is it possible to do that ? maybe guide me with
some logics?
cos currently i am having problem as i have a few users, and my shared object stores only 1 user’s datas.
pls help~ thanks a lot~