How can I start talking to someone I see every morning?
Well, it depends generally on the person's age, gender and class so it will be quite difficult to explain but from the look of things, I would guess that you mean your age class and probably the opposite gender who you are probably having interests in.
How it goes therefore is for you to first, greet the person with a warm smile for about some days and eventually, when you greet, you can ask how the person's night was and if the weather was convenient for a good night's sleep.
When for some weeks, the person notices you are interested in his/ her well-being, then you would be welcomed into the problem sharing zone and soon, the relationship grows till it heads to where you want it to go.