Write a Registry key

using Microsoft.Win32;
...
RegistryKey masterKey = Registry.LocalMachine.CreateSubKey
("SOFTWARE\\Test\\Preferences");
if (masterKey == null)
{
Console.WriteLine ("Null Masterkey!");
}
else
{
try
{
masterKey.SetValue ("MyKey", "MyValue");
}
catch (Exception ex)
{
Console.WriteLine (ex.Message);
}
finally
{
masterKey.Close();
}
}