I want to know about universe how it will be begin.
1 year = 1 hour.Black Holes
A black hole is a place of such high density - so much mass has been shoved into so little space - that spacetime has been curved (general relativity says that mass curves space, like a ball on a sheet of rubber) so much that nothing can escape, not even light. As such, it is possible to travel into a black hole, but it isn't possible to get out of a black hole.
As for its mass, that depends. Since it depends on density, there are tiny black holes or huge black holes. Tiny ones evaporate quickly, however, due to Hawking Radiation, so we'll focus on bigger ones. (It should be noted that we know black holes exist, but we have never seen the smaller ones.) Most black holes are 10 to 100 solar masses (one solar mass is the mass of our sun; the sun is 333,000 times the mass of Earth), but there are supermassive black holes, like those at the centers of galaxies, that can be millions or billions of solar masses.
Finally, time is warped around a black hole (general relativity says that not only does mass curve space, it also curves time), but it is not quite as simple as that. Look at this question for more information about how time curves around a black hole.
Wormholes
A wormhole is a purely hypothetical construction. The idea is that it is a black hole and a white hole bound together. The problem is that the connection would collapse very quickly without negative energy, which is also hypothetical. So a wormhole is hypothetical, white holes are hypothetical, and negative energy is hypothetical. Wormholes aren't really scientific. (A white hole is like the exact opposite of a black hole - instead of sucking everything in, it shoots everything out. You can exit a white hole, but you cannot enter a white hole.)
Hope this helps!
Resources
You can learn more about black holes here, about Hawking radiation here, and about general relativity here. You can learn about white holes here, wormholes here, and negative energy here.
