How to insert and remove strings from tree class and treenode class in C++?

I have a file of strings, each of which is in a separate line. I want to insert these strings to my treenodes. My codes can be compiled fine but when I load my string file, there is a segmentation fault. How do I fix it and are my codes correct to make a tree? If I want to remove each node and print it on screen, what would the remove function be? My header file:

#ifndef TREE_H
#define TREE_H

#include <iostream>
using namespace std;

struct TreeNode
{
    string Key;
    TreeNode *left;
    TreeNode *right;
};

class Tree
{
    private:
        TreeNode *root;

    public:
        Tree();
        ~Tree();
        string Insert(TreeNode *newNode);
        string Delete(string Key);
    private:
        void ClearTree(TreeNode *T);
};

#endif

Here is my cpp file:

#include <iostream>
#include "try1.hxx"
#include<fstream>
#include<string>
#include<sstream>

using namespace std;

Tree::Tree()
{
    root = NULL;
}

Tree::~Tree()
{
    ClearTree(root);
}

void Tree::ClearTree(TreeNode *T)
{
    if(T==NULL) return; 
    if(T->left != NULL) ClearTree(T->left);
    if(T->right != NULL) ClearTree(T->right);
    delete T;
}

string Tree::Insert(TreeNode *newNode)
{
    TreeNode *temp;
    TreeNode *back;

    temp = root;
    back = NULL;

    while(temp != NULL)
    {
        back = temp;
        if(newNode->Key < temp->Key)
            temp = temp->left;
        else
            temp = temp->right;
    }

    if(back == NULL) root = newNode;
    else
    {
        if(newNode->Key < back->Key) back->left = newNode;
        else back->right = newNode;
    }
}

int main(int number_of_arguments, char** arguments)
{
    Tree *theTree;
    TreeNode *newNode;
    theTree = new Tree();

    string line;
    if (number_of_arguments != 2)
    {
        cout << "ERROR: incorrect command line parameters" << endl;
    }

    ifstream myfile;
    myfile.open (arguments[1]);
    if (myfile.is_open())
    {
        while (getline(myfile, line))
        {
            newNode = new TreeNode();
            newNode->Key=line;
            newNode->left = newNode->right = NULL;
            theTree->Insert(newNode);
        }
    }else cout << "The file doesn't exist" << endl;
}