We made a recent change such that when you are creating or editing an article the "post to" selection always shows LessWrong. In the case that you don't yet have enough karma to post to LessWrong then it will be grayed out and have a message next to it explaining why.

Old versions of IE unfortunately don't honor the grayed out option. In this case you can select LessWrong but submitting will inform you that you can't yet submit to the LessWrong category (of course you can always save to your drafts).