ACL for different groups that have different users

Hi All
I have created four groups using Organic Group module of Drupal.Now lets suppose these groups have given name as A,B,C,D,now lets say a person subscribe for a group A,I have to restrict that person from displaying the contents from other groups i.e from group B,C,D.I have tried this with ACL but not found proper solution.
Will anybody please help me out,how can i do this,please specify in brief,thanks in advance.
Regards,
Rohit