Taking your comments into consideration, and the lack of information on the Big 7, this is what I can find regarding creating a newsgroup in the Big 8.
Before a new Big 8 newsgroup can be created, an RFD (Request For Discussion) must be posted into the newsgroup news.announce.newgroups, which is then discussed in news.groups.proposals. Once the proposal has been formalized with a name, description, charter, the Big-8 Management Board will vote on whether to create the group. If the proposal is approved by the Big-8 Management Board, the group is created. Groups are removed in a similar manner.
There is a fairly recent article here that takes you through the steps for creating one. To be honest it seems quite complex, however it may just be a perception and it really is a lot easier to get it approved.