Where is permissions part?

Once logged in as the admin you can change the permissions for the site by clicking on Administer, then Accounts and finally Permissions. These are permissions for the Roles of the users, ie: random visitor to your site (anonymous user) and registered members (authenticated user). You can add more to these by clicking on Roles. If you want to change the Roles of any user click on Administer, then Accounts, which will list all the accounts. Click on Edit Account and at the bottom of that page you will see a drop down list to change the user's role and access control. Click save. You're done.