C++ Linked List: variable issue

struct List
{
     Post *p;  //a random class
     List *next;    
};

and i use this to insert data

List *help;
help=(*leaf)->start; //leaf is a node where is the start of the list
while(help!=NULL)
    help=help->next;
help=new List;
help->p=new Post()
help->next=NULL

why this doesnt work?

sorry for my bad english and if this is too easy .. Thanks again