Posting clarification & additional info
To clarify the part yesterday, in which I mentioned you shouldn't divide your story into chapters/parts and post over several days:
If you're posting on LJ, just about everyone's story is going to be too long for one post, so stories will need to be divided into more than one post. However, all chapters/parts should be posted on the same day.
Generally, the way I've done it, and seen it done, is to post each chapter/part separately, then create a Master Post, linking to all the parts from there. Then, on this site, you create your post, using the header information requested, and link it back to your Master Post.
I hope this is clearer, although, if there are any questions, don't hesitate to ask.
For the additional information - I've created a collection on AO3. I can't insist everyone put there story up there, however, it is a wonderful site to use, as it allows for much longer stories in a single entry, and allows people to download each story in multiple formats, for ease of reading. So the collection is 'Smallville Big Bang', but I also made a sub-collection simply called Smallville Big Bang 2011 or SVBB2011 for short.
You do need to be a member to post there, but it's easy enough to get an invite (although the wait to be sent one can be lengthy). Please at least consider putting your story up over there, and if you do, please fill in the appropriate box on their form with our collection name. I'll say thanks in advance for at least considering it.