Once the boys had left the shopping centre, they walked towards the Leeds & Liverpool Canal. It is said that James was dropped on his head here, and started to cry. Despite having a bump on his head and the fact that he was crying, the boys were barely challenged - they saw a total of 38 people from leaving the shopping centre to arriving at the train tracks.
They then arrived at the train tracks, where Venables and Thompson tortured young James and eventually attempting to hide him under rubble.
The boys started by throwing paint in Bulger's eye (paint which was shoplifted earlier that day) and then proceeded to kick him and stomp on him as well as throwing bricks and rocks at him. They inserted batteries into his mouth and then dropped a 10kg iron bar onto him which killed the child. It is also thought that there might have been a sexual motive behind the attack as many items of Bulger's clothing such as his underwear were removed, as well as reports of batteries also being inserted into his anus as well as his mouth - though this has not been proven.
After the murder, Venables and Thompson then covered Bulgers' head with bricks and rocks and tried to make it seem like the death was down to a train on the train tracks. Later, a train cut Bulgers' body in half - though it was confirmed by a pathologist that James had died before the train had struck.
For more information on the murder, click here.
Ref: http://en.wikipedia.org/wiki/Murder_of_James_Bulger