Create a new folder in your module called security. Add 2 files ir.model.access.csv and an xml file with any name. (here : student_security.xml ). Specify these files in the update xml portion in the __openerp__.py file of the module as :

 'update_xml': ["security/student_security.xml",
                "security/ir.model.access.csv",
                  ............other files in the module...................
               ]

in the xml file you can create groups for users. For eg:

<?xml version="1.0" encoding="utf-8"?>
<openerp>
<data>

    <record id="group_student" context="{'noadmin':'True'}" model="res.groups">
        <field name="name">Student</field>
    </record>
</data>
</openerp>

After upgrading the module This creates a group Student. Now you can add any user that you create or an existing user to this group via the client. Settings/users/users/Access rights. . you will be able to see your created group as a boolen field in the section "Other" Then you can set the permissions for this group in the ir.model.access.csv file. An example for this file would be there in the module sale/security. you can refere that.