Were you really expecting it in three days? It takes at least five and if any questions come up, maybe a couple of weeks. When you efiled, it should have notified you within a few minutes that they had received it. Then the wait begins for them to look at it and actually accept it. Once accepted, it goes through some pretty simple checks for accuracy and in short order they should approve it and give you your refund.
I filed mine today and before I left the page - in seconds - Turbo Tax notified me that it had been received by the IRS. If that didn't happen then you will have to take steps to determine whether or not they actually have it as described in the other answers.
