According to evolutionists the "Big Bang" theory is how everything started, however there are many problems with it.
1) Where did the matter first come from?
2) A part of the "Big Bang" theory includes the "Big Squeeze" which says that all matter was squeezed into one area, so were did the energy of the squeeze come from?
The second part of the "Big Bang" was when everything exploded out from the "Big Squeeze" into gas and planets and all those other things.
3) The "Big squeeze" turning into an explosion that formed everything would not work considering that the gravity of everything hold everything on place and if it was supposed to be an implosion everything would be put into one gaint mass.