Docs here have an example in C#: http://seleniumhq.org/docs/03_webdriver.html
using OpenQA.Selenium.Firefox;
using OpenQA.Selenium;
class GoogleSuggest
{
static void Main(string[] args)
{
IWebDriver driver = new FirefoxDriver();
//Notice navigation is slightly different than the Java version
//This is because 'get' is a keyword in C#
driver.Navigate().GoToUrl("http://www.google.com/");
IWebElement query = driver.FindElement(By.Name("q"));
query.SendKeys("Cheese");
System.Console.WriteLine("Page title is: " + driver.Title);
driver.Quit();
}
}