Another question pertaining to the speed of light and einstiens theory.?

Ok, I am trying to understand why its against the laws of physics to travel the speed of light. I was told that if I was on a ship traveling the speed of light for 1 year that many more years then that would p for the people on earth not traveling the speed of light. Is this correct? If so, why? My second question is lets say I am in a spaceship that is able to reach light speed instantly and I am going to race a beam of light from a super powered light to the finish line which is exactly one light year away. There is a person standing at the finish line staring accross it. If we both start at the same time what will the person at the finish line see cross it first? Will my space ship and the beam of light cross it at the same time or will the person see the beam of light cross the finish line before me?