trees

I know in my main function the root isn't pointing at anything but I'm not sure what to make it point to too be able to traverse the tree.

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#include <iostream>
#include <fstream>
#include <cstdlib>

using namespace std;
ofstream outfile;
ifstream infile;
struct Node
{
    int value;
    Node *Lefty;
    Node *Righty;
};
Node *root;
Node *NewNode();

void Insert(Node *c, int NV)
{
    Node *p, *tp;
    p = NULL;
    while(c != NULL)
    {
        if(c->value > NV)
        {
            p = c;
            c = c->Lefty;
        }
        else
        {
            p = c;
            c = c->Righty;
        }
        tp = NewNode();
        tp->value = NV;
        if(NV < p->value)
        {
            p->Lefty = tp;
        }
        else
        {
            p->Righty = tp;
        }
    }
}
Node *NewNode()
{
    Node *temp;
    temp = new Node;
    temp->value = 0;
    temp->Lefty = NULL;
    temp->Righty = NULL;
    return temp;
}
void InOrder(Node *c)
{
    if(c == NULL)
        return;
    else
    {
        InOrder(c->Lefty);
        cout << c->value << " ";
        InOrder(c->Righty);
    }
}
void PreOrder(Node *c)
{
    if(c == NULL)
        return;
    else
    {   cout << c->value << " ";
        PreOrder(c->Lefty);
        PreOrder(c->Righty);
    }
}
void PostOrder(Node *c)
{
    if(c == NULL)
        return;
    else
    {
        PostOrder(c->Lefty);
        PostOrder(c->Righty);
        cout << c->value << " ";
    }
}
int main()
{
    int v;
    infile.open("TreeInData.txt");
    infile >> v;
    Insert(root, v);
    InOrder(root);
    PreOrder(root);
    PostOrder(root);
    return 0;
}
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