Hi
As i understand it there was the big bang which created the dimensions up/down left/right forward/back and possible time (although some scientist are questioning whether time exists) and forced the energy into matter which can be broken down again (eg : if u lite a fire). The universe expanded at the speed of light because there was nothing to get in its way.
Outside of the universe there is no dimensions so u cannot see it, u cannot go into it, it is absolute nothingness. If u could go faster than the speed of light to the edge of the universe and kept going u would come back on yourself and then be going inward towards where the big bang started.
Thats how is see it anyway.