Since its introduction in Windows 95, the registry has more often than not intimidated developers. The registry acts as a central repository of information for the operating system and the applications on a computer. When you store information in the registry, choose the appropriate location based on the category of information being stored.

Here is how to write and read from the registry using C#.

// i.e : string  myValue = readFromRegistry("Software\\Myapp","TheKey","TheValue");
       public static void saveToRegistry(string subkey, string key , string value) {
            // Save user prefs to reg.
            RegistryKey regKey = Registry.CurrentUser;
            regKey = regKey.CreateSubKey(subkey);
            regKey.SetValue(key, value);
        }

// i.e : string  myValue = readFromRegistry("Software\\Myapp","Thisthekey");
        public static String readFromRegistry(string subkey, string key){
            // Retrieve user prefs from reg
            RegistryKey regKey = Registry.CurrentUser;
            regKey = regKey.CreateSubKey(subkey);
            return (string)regKey.GetValue(key, "");
        }

Find out more :MSDN Microsoft