There are predefined roles that will generally work in most situations, and If not you can define your own. For your example where you want only selected users to have permission to upload content to a space, go to "Manage Space Users" for the space and then invite the selected users and assign the role of Contributor.
* Consumer: Allows read properties, content, and children of a node.
* Editor: Adds to consumer privileges the ability to write nodes (properties, content, and children) and execute CheckOuts in nodes with aspect lockable.
* Contributor: Adds to consumer privileges the possibility of adding children and execute CheckOuts in nodes with aspect lockable.
* Collaborator: This role has the same capabilities as Contributor and Editor.
* Coordinator: This role has all privileges including the possibility of taking ownership of nodes, and changing its owner.
* Administrator: Same as Coordinator, it is defined for backward compatibility.
I gave contributor role for the previlaged group and no access role to everyone group.
So now this space is visible only to the members of previlaged group. so this one worked out.
But i want the docs uploaded by the previlaged group to be secure,if some one from the everyone group searchs these docs it should not be visible to them.
I suppose that you`ve already solved it, but If you haven`t, I would check the option "Inherits permissions of parent space ", do not be going to be that the space is inheriting permissions for the group everyone.
