the mysteries within the forest (a nightmare before christmas story)

Chapter 4: Oogie boogie

After eating, Jack, Sally and me left to what used to be the home of the boogie man in search of the children from Alans picture.

Inside it was dark and seemed
abandoned, but, then again, all of halloween town looks this way. The only thing in site are dollar bills flying around. Suddenly we see a figure run in front of us. I ran behind it, "Charlotte wait don't go alone" said Jack and afterwards Sally grabbed his hand and followed me. After running after it for a while, the figure stops; "Jack! Im sorry, Im sorry, we thought it was a joke..." We starred at each other puzzled. Then the figure walked into the light. It was the witch child in the picture..."Shock" said Jack. "We where just having fun...we didn't think he would actually hurt anyone..." Said Shock.
"Shock what happened?" Asked Jack.
" He took part of the ghosts memories too..." Said Shock.
"Alan... Why did he do that?" I desperately ask.
She ignored me and once again approached Jack; "You need to save them...All halloween town is in grave danger..." Just then the building began to shake; "Charlotte, you are the door to freedom but Alan is a messenger with the key..." She got cut off by a rope that grabbed her leg and dragged her into a circular entrance."hide" were her last word. We tried to move closer to help her but we got trapped by a net.
We struggled to get out but it was useless. Help. Not so long after, Alan appeared with a knife and cut us loose. "So this is the famous ghost boy" said Sally. When Alan realized he was spotted he tried running away; "Alan, Stop!" The boy stopped " You don't need to go. We are all friends and we are going to help you. Please come with me...stay..." Alan thought for a while and came with us.

Still, Things just keep getting more confusing. What did Shock mean by "being the door of freedom and Alan being the messenger, the key"? What is Oogie up to? What is Alan? What is my role in this story? Who am I?