Online, phone, instore?
I actually mailed mine in. They don't offer online apps currently. They allow you to prefill them out then mail or fax them in. Not sure if you can apply by phone or not. Hope that helped.
I did the same by mailing it in, I called in to ask what was the "status" of my application over three weeks of mailing it in. They asked a few questions and were one of the nicest CITI CS I have met.