What is a good way to code a messagebox in C#, like the AfxMessageBox in used in Visal C++?

For code like the following, there must be a "using..."
declaration missing because I got this error:
error CS0246: The type or namespace name 'MessageBoxButtons' could not be found (are you missing a using directive or an assembly reference?)

string message = "blah";
string caption = "blah";
MessageBoxButtons buttons = MessageBoxButtons.YesNo;
DialogResult result;

result = MessageBox.Show(message, caption, buttons, icon);

Also, is there a good way to write information out to a log file?