I have a 2002 kia sedona ex and I'm ordering my blower motor tomorrow... where do I start? Is it on the fire wall or under the dash? And then what

Take a peek under the passenger compartment of the dash.

I don't know about your specific vehicle, but they can be "fun" to replace.

If the brushes are worn, all you need to do is got to a vacuum cleaner store and possibly file brushes to fit.