Contact members of a group or group type by sending them an email.
Go to your group and select Email all members.
You can also email all members of a group type. Select the group type then Email all members.
To send an email to a more specific set of people, use the filter bar or manually select the members you need to contact
There's not a way to add an attachment to an email; instead, add the file to Resources and point people to that resource.