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.
Communicate User Rights
If a Contact has Communicate User Rights, when logged in they will be able to see their Dashboard, Communicate menu and their own Tasks.
A User with Communicate User Rights can send new Email and Group Messages.
Note: A User with Communicate User Rights can send to Contacts and Groups but will not have the permissions to view Contact or Member details.