To create a User, e.g. a committee member, select Organisation > Users and Roles
If the Contact is already in the Users list, you can adjust their User Rights by selecting Edit User Rights and clicking on the appropriate check box item to unlock it - or, give them the permissions for that level.
If the Contact isn't yet a User, you can add them and give the appropriate User Rights.
Settings User Rights
If a Contact has Settings User Rights, when logged in they will be able to see their Dashboard, Organisation Details (Details, Logo and Colours, Social Networks, Public Contacts, Public Facing Page, Sponsors and Scratch Pad, Date, Time & Currency), the Activity Feed and their own Tasks.
Contacts with Settings User Rights would generally be able to edit and maintain the Public Facing Page as well as the logo and colours.