tire adjustment

Today before a ride I glanced down and noticed that my tire was a fraction off
center to the seat post (you couldn’t tell unless you really looked). As a
beginner with a week experiance of riding I am not able to determine if this is
a problem or not. I can ride forward on a flat surface for a long time without
terrible difficulty so it doesn’t seem to be effecting me too badly. I was just
curious if I should make an adjustment. And if I did, how? I own a 20" Cyclepro.
Also, for anyone who has a Cyclepro, does a Miyata seat fit on this uni? And if
it does, do I need to buy the post that comes with it?