Changing 700c x 28mm wheel/tire to 650c? I'm new to the biking community, I was wondering if I would be able to change my wheel/tire from 700c to 650c since I am short. How would I go about it, any recommendations for wheel/tires? I have a Retrospec Mantra Single Speed XS 43cm frame with 700c tires.
If this is your bike then no.  It has rim brakes, and they won't line up properly if you try to install smaller wheels.
You say that you are short; the only thing that smaller wheels will change is the standover height (height of the top tube).  All the rest of the bike's geometry will be the same, including distance to the cranks and distance to the handlebars.  It might actually cause problems because smaller wheels will put your bottom bracket closer to the road, increasing the chance of a pedal strike.  (Unless you also change your cranks.)
Perhaps you simply need to buy a smaller bike?