What you can do on Classlist varies according to what admin status you have as a member; ie whether you are a parent without admin rights or a Class Admin, Community Rep or Ambassador.
The Ambassador role is automatically given to the initial creator of the site, but can also be assigned to other key parents who play an active role in the school community such as PTA postholders. Ambassadors can access all areas of the site and can moderate and manage content.
The Class Admin role is usually allocated to someone who can act as the representative for the other parents in his/her child's class/year. If your school operates a system of Class Reps this role is perfect for them. Class Admins can approve parents and view most of the admin features on Classlist but only in relation to the class/year which they represent.
Staff Admins have the same administrative powers as Ambassadors but do not have any access to the parent side of Classlist. This means that they cannot access or moderate any parent-created content (such as posts or listings) but can still send out announcements and help with the approval of parents. They can also delete pupils (eg when they have left the school).
Community Reps can use the admin features to create announcements and community events, but have limited access to the other administrative features. This role is suited for parents with a specific position in the parent community which may not be the same as a PTA position, eg Fair Funding Campaign Officer, Second Hand Uniform Sales, or just someone who is keen to help out from time to time.