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.
Events User Rights
If a Contact has Events User Rights, when logged in they will be able to see their Dashboard, all Events and their own Tasks.
Contacts with Events User Rights will be able to create, edit and view all Events. They will be able to view Events created by other Users that have not been marked as public.
A Contact with Events User Rights will also be able to see the Attendees of Events (although not view the Attendees Contact details), as well as view Transactions and issue Invitations to attend.