I am using cognos 8.3 Cognos Administratration (SQL Server 2005).
I am able to create group, role and folder but not sure how to create user and member.
Thanks
You don't create users in Cognos. You create them in your authentication source (like LDAP) and Cognos connects to that authentication source.
If you can through Cognos Connection, establish a connection to an AD source if possible. AD makes it very easy to create new security groups and users. Replication time may depend (The time it takes cognos to recognize a new user/role).
If you can connect to AD, stop cognos, make the needed changes under Security (cognos connection) and save. Restart cognos services and click on the details button to ensure the change is registered in the content manager. You shouldn't need to restart the server to make it work.
You also may need to be granted firewall rules depending your environment to AD.