Question

how far the edges of our visible universe? nd how can we calculate them...

Answer 1

Direct quote from wikipedia:
"
In Big Bang cosmology, the observable universe consists of the galaxies and other matter that we can in principle observe from Earth in the present day, because light (or other signals) from those objects has had time to reach us since the beginning of the cosmological expansion. Assuming the universe is isotropic, the distance to the edge of the observable universe is roughly the same in every direction—that is, the observable universe is a spherical volume (a ball) centered on the observer, regardless of the shape of the universe as a whole. Every location in the universe has its own observable universe which may or may not overlap with the one centered on the Earth.
"

So the answer to that question is "it depends". Our observable universe is simply as far as we can see from Earth. Since that is dependent on what we can actually SEE, this means we have to wait for the light from these distant sources to reach us. We have estimated that the universe is 12-14 Billion years old. So with Earth at the center we essentially have a "horizon" which we cannot peer past simply because the light hasn't reached us yet. This means our "visible universe" is roughly 24-28 billion light years in diameter.