Well I would imagine they are getting alot of story submissions right now because of the valentines competition, so thats probably why it is taking a while.
First, go to your author page, click submissions and then click view.
Scroll through your list until you find the stories you've submitted that aren't posted yet. There should be a blue link in the bottom right cornor that says "pending." If it doesn't say pending it will will say "rejected", in which case you can click the link and find out why, or it will say some like "In preview-please submit", in which case click the link, scroll down to the bottom, and press submit.
If it doesn't show up at all, the server probably burped while you were submitting it and you should submit the stories all over again.
If you emailed them, it's going to take a few weeks.