Hello postdar,
thank You for the compliments.
First of all, the title of Your question is very misleading, because in BwPostman You can't create user groups and in Your description You talk about a csv file…
I would suggest, You read the
manual
and do the steps one by one described there.
In short: You have to create a mailing list, import the subscribers of Your csv file to this mailing list, select this mailing list at the first tab at newsletter edit. Then You are able to send Your newsletter.
If You want to send to a user group, then You have to create Joomla users of Your csv file users, assign these users to a Joomla user group and select this user group at the first tab at newsletter edit.
Hth
Romana
