best practices in creating a product backlog in scrum [closed]

Question

I am new to scrum, project management in general, and i am having problems deciding what to call a feature or a sub-feature (which are tasklists to creating that feature?) especially for the standard things we have in every web app.

So i am looking for best practices on how people are creating product backlogs for a typical website software (users, profiles, admin, front-end) .

I have this in mind as an example.

 - feature: home page

 - feature: contact us page

 - feature: admin panel
            - create user
               + create database (tasklist)
               + write stored procedures (tasklist)
            - delete user
            - add content
            - delete content

 - feature: subscribe 
            - create subscribe page

Also, how granular is too granular?