How can I write a heap_insert function for a heap of nodes as a binary tree, with C

In C language only with these struct node and struct heap Suppose that the heap data structure is implemented with the modified binary tree nodes defined below.

• The parent variable in the node data structure is a pointer on the parent of the corresponding node (providing access from a node to its parent). The variable 'last_added' in the batch data structure shows the sign of the latest 'node' to data making

struct node {
     int key;
     struct node * parent, * left_link, * right_link;
};
struct heap {
struct node * root;
struct node * last_added;
}

void heap_insert(struct heap *heap,int key){
//-- the code --
}