sp15OAuth.cs

using (ClientContext clientContext = new ClientContext("https://yoursite.sharepoint.com/"))
{
    var passWord = new SecureString();

    foreach (char c in "yourpassword".ToCharArray()) passWord.AppendChar(c);

    clientContext.Credentials = new SharePointOnlineCredentials("loginname@yoursite.onmicrosoft.com", passWord);

    Web web = clientContext.Web;

    clientContext.Load(web);

    clientContext.ExecuteQuery();

    Console.WriteLine(web.Title);

    Console.ReadLine();
}