I brush my teeth all the time but they are still yellow. what can help them get white quickly?

Tooth whitening: Yellowness can be due to tartar build up or smoking or the food that you eat after doing a cleaning at the dentist, if it continue you can do whitening.

You might try: A whitening system (over the counter) like crest whitestrips. If you would prefer a more predictable outcome then a professional whitening that can be safely performed by your dentist. Hope this helps.