I'm not sure I understand what you're trying to find out. There is no "galactic center of our universe" nor is there a "center" to the universe as a whole (that we know of).
Do you mean, "where is Earth relative to the center of our galaxy?" That we can answer, because we know where the center of the Milky Way is located, in celestial coordinate. That is, I can point it out to you on the night sky, or using a planetarium program on a computer that generates a map of the night sky.
If you are interested in a geometric exercise of some sort, then you'll need to understand the galactic coordinate system.
Tell us what you are trying to figure out and we may be of more help.
Meanwhile, perhaps this visualization will help:
The universe is not only stranger than we imagine, it's stranger than we CAN imagine. --- JBS Haldane
Come visit me at Comanche Springs Astronomy Campus (we're on Google Maps) in Texas.