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 Invite them and give the appropriate User Rights.
Pages User Rights
If a Contact has Pages User Rights, when logged in they will be able to see their Dashboard, Pages and their own Tasks.
Contacts with Pages User Rights would generally be able to view all Pages and create new Pages, Menus and External Link items.
If the User is required to maintain the Public Facing Page in addition to the Pages, then Settings User Rights also needs to be applied.