C++ - Write at the end of a file and skip over the rest

So I have a text file:
Dylan
6

where Dylan is the player name, and 6 is high score.
I want to make it write a new player high score, but when I do it, it overwrites what I already have. 
(here is the rest of my code if you wanna see it)
cin >> chName;
ofstream myfile;
myfile.open("score.txt");
myfile << chName << "\n" << iScore << "\n\n";
myfile.close();

How would I make it skip over what is already written? (also have it do this in the future)
I am very new to C++, so sorry if my question is vauge
Thanks

You should append to the file: (ios::app)
ofstream myfile;
myfile.open ("myfile.txt", ios::out | ios::app);
if (myfile.is_open())
{
    myfile << "This is a line.\n";
    myfile << "This is another line.\n";
    myfile.close();
}

http://www.cplusplus.com/doc/tutorial/files/