user access manager that does not send registerer to dashboard

Is there a way for the ‘group’ to be automatically assigned so they do not get into a ‘wordpress’ log-on and into dashboard – i have to check the ‘user group’ box before they are sent to the proper site and view pages (not build or upload pages – just want them to have access to read and post comments) they have no clue what to do when they are inside the dashboard (and I don’t want them in there)

Re-worded: I don’t want new users to get to a dashboard – only to the site that the usergroup has given them permission to read the pages.. ??