How do I insert the new Node in a B-Tree?

Below is the code I have, what is the code to insert the new node

#ifndef BTree_h

#define BTree_h

#include

#include

#include

using namespace std;

#define M 4

struct record

{

int idNo;

string name;

string surname;

};

typedef struct record Record;

//====================================================

//B-Tree Node Class code

//====================================================

class BNode

{

private:

vector pointer;

Record data[M];

BNode* parent;

public:

// Constructor

BNode();

//Accessors

string getData();

BNode* getPtr(int x){return pointer[x];}

//Mutators

bool setData(int, string, string);

void setPtr(int x, BNode* ptr){pointer[x] = ptr;}

};

BNode::BNode()

{

pointer.resize(M+1);

for (int x = 0; x < M; x++)

{

pointer[x] = NULL;

data[x].idNo = 0;

data[x].name = "";

data[x].surname = "";

}

pointer[M] = NULL;

parent = NULL;

}

string BNode::getData()

{

string str = "";

for (int x = 0; x < M; x++)

{

str.append("[");

str.append(to_string(data[x].idNo));

str.append(" ");

str.append(data[x].name);

str.append(" ");

str.append(data[x].surname);

str.append("] ");

}

str.append(" ");

return str;

}

bool BNode::setData(int num, string first, string last)

{

if (data[M-1].name != "")//Node is already full

return false;

int x = 0;

for (; x < M && data[x].name != ""; x++);

if (x > 0)

{

while (data[x-1].idNo > num)

{

data[x] = data[x-1];

x--;

}

}

data[x].idNo = num;

data[x].name = first;

data[x].surname = last;

return true;

}

//====================================================

//B-Tree Class code

//====================================================

class BTree

{

private:

BNode* root;

BNode* insertHelper(int, string, string);

public:

BTree(){root = NULL;}

//Mutator

void insert(int, string, string);

void remove(int);

//Accessor

string display();

};

void BTree::insert(int num, string first, string last)

{

root = insertHelper(num, first, last);

}

BNode* BTree::insertHelper(int num, string first, string last)

{

BNode* ptr = NULL;

if (root == NULL)

{

ptr = new BNode();

ptr->setData(num, first, last);

return ptr;

}

//ELSE

//

// Where should the new node be inserted??????

//

return ptr;

}

#endif /* BTree_h */