trying to figure out how to use external values (.txt document) to store the values and using those saved values as the values in my .cpp code

Question

I have been asked to save my values to an external file in c++ I am having difficulty having my code access the .txt file and was wondering if anyone could identify what I am missing. In this case the code is taking a string from my .txt file and encrypting it in a very basic manner. For some reason I am getting a bunch of random characters as my original input when I would Like it to simple encrypt "John Doe"

# include<fstream>
#include<iostream>
#include <string>
using std::ifstream;
using std::ofstream;
using std::endl;
using namespace std;

int const LENGTH_OF_STRING = 10;

int main() {
    ifstream instream;
    ofstream outstream;

    instream.open("infile.txt");
    outstream.open("outfile.txt");

    char myMsg[LENGTH_OF_STRING];
    char encryption[LENGTH_OF_STRING];

    cout << myMsg; // this is returning a crazy string of characters therefore I must be missing the command to let the program know where to get the information from

    for (int i = 0; i < strlen(myMsg); i++) {
        int asciiNum = (int)myMsg[i];
        int newAsciiNum = asciiNum + 100;
        char newEncryption = (char)newAsciiNum;

        encryption[i] = newEncryption;
        outstream << myMsg[i] << " = " << asciiNum << "\t"
            << " new ascii number = " << newAsciiNum << "\t"
            << "New encrypted character = " << newEncryption << endl << endl;
    }

        outstream << endl << "encrypted message = " << encryption << endl << endl;

    instream.close();
    outstream.close();

    system("PAUSE");
    return 0;
}

Any help would be greatly appreciated

P.S. my infile.txt looks like:

myMsg = "John Doe";

encryption = " ";