Yes, alt.tv.southpark.creative has been created last week, yet it doesn't seem like many of us (myself included) have it on their news servers yet.
BUG YOUR NEWS ADMINISTRATORS FOR IT, folks. In the meantime, try to post fanfics and other literary works on the new newsgroup, and cross-post them here until almost everybody has access to the new group.
Already did...sent 'em a pleading email! :) About how long does it normally take for a newsserver to pick up a new group? <hopes my ISP will pick it up> BTW, how does one go about crossposting? (Forgive me, I'm a hopeless computer illiterate)
Typically, in your newsreader, when you post, you can type multiple groups into the Newsgroup: field. To crosspost to alt.tv.southpark and alt.tv.creative, you would type this: "alt.tv.southpark,alt.tv.southpark.creative" (without the quotes).
Hard to say... Usually if the group is a subgroup of another then there are lots of people to bug the news admins, so they add it quickly... It takes less than a week in most cases. In answer to your second question, it depends which newsreader you're using. However, there should be a "newsgroups:" field somewhere, where it will say alt.tv.southpark. You then put a comma, then add the next group. For instance:
alt.tv.southpark,alt.tv.southpark.creative
Sometimes a space is required between the comma and the next group, it depends on your newsreader.