using CMS.SiteProvider;

using CMS.SettingsProvider;

using CMS.CMSHelper;

using CMS.TreeEngine;

...

        string siteName = CMSContext.CurrentSiteName;

        string aliasPath = "/News";

        string cultureCode = "En-us";

        // Tree provider

        TreeProvider provider = new CMS.TreeEngine.TreeProvider(CMSContext.CurrentUser);

        // Get document of specified site, aliaspath and culture

        TreeNode node = provider.SelectSingleNode(siteName, aliasPath, cultureCode);

        // If node exists

        if (node != null)

        {

            // Edit and save document node

            node.DocumentName += " changed";

            node.Update();

            // Create update task

          SearchTaskInfoProvider.CreateTask(SearchTaskTypeEnum.Update, PredefinedObjectType.DOCUMENT, SearchHelper.ID_FIELD, node.GetSearchID());

        }