Create new item in Sitecore --> references here: http://briancaos.wordpress.com/2011/01/14/create-and-publish-items-in-sitecore/

createNewItem.cs

// The SecurityDisabler overrides the current security model, allowing you
// to access the item without any security. It's like the user being an administrator
using (new Sitecore.SecurityModel.SecurityDisabler())
{
  // Get the master database
  Sitecore.Data.Database master = Sitecore.Data.Database.GetDatabase("master");
  // Get the template to base the new item on
  Items.TemplateItem template = master.GetItem("/sitecore/templates/Sample/Sample Item");
 
  // Get the place in the site tree where the new item must be inserted
  Item parentItem = master.GetItem("/sitecore/content/home");
 
  // Add the item to the site tree
  Item newItem = parentItem.Add("NameOfNewItem", template);
 
  // Set the new item in editing mode
  // Fields can only be updated when in editing mode
  // (It's like the begin tarnsaction on a database)
  newItem.Editing.BeginEdit();
  try
  {
    // Assign values to the fields of the new item
    newItem.Fields["Title"].Value = "Value1";
    newItem.Fields["Text"].Value = "Value2";
 
    // End editing will write the new values back to the Sitecore
    // database (It's like commit transaction of a database)
    newItem.Editing.EndEdit();
  }
  catch (System.Exception ex)
  {
    // The update failed, write a message to the log
    Sitecore.Diagnostics.Log.Error("Could not update item " + newItem.Paths.FullPath + ": " + ex.Message, this);
 
    // Cancel the edit (not really needed, as Sitecore automatically aborts
    // the transaction on exceptions, but it wont hurt your code)
    newItem.Editing.CancelEdit();
  }
}