SPWebCollection.Add method (String, String, String, UInt32, SPWebTemplate, Boolean, Boolean)

public SPWeb Add(
	string strWebUrl,
	string strTitle,
	string strDescription,
	uint nLCID,
	SPWebTemplate WebTemplate,
	bool useUniquePermissions,
	bool bConvertIfThere
)

public override void FeatureActivated(SPFeatureReceiverProperties properties)
{
    // Get the web site where the feature is activated.
    SPWeb parentWeb = properties.Feature.Parent as SPWeb;
    if (parentWeb == null)
        return;

    SPWeb childWeb = null;
    string childName = "ourwiki";

    // If a subsite by that name exists, open it.
    string[] webs = parentWeb.Webs.Names;
    if (webs != null && Array.IndexOf(webs, childName) >= 0)
    {
        childWeb = parentWeb.Webs[childName];
    }

    // Otherwise, create the subsite.
    if (childWeb == null)
    {
        string title = "Wiki";
        string desc = "A place to capture knowledge.";
        uint lcid = parentWeb.Language;

        string templateName = "WIKI#0";

        childWeb = parentWeb.Webs.Add(childName, title, desc, lcid, templateName, false, false);
    }

    // Let the subsite use the parent site's top link bar.
    childWeb.Navigation.UseShared = true;

    // Get a collection of navigation nodes.
    SPNavigationNodeCollection nodes = null;
    if (parentWeb.Navigation.UseShared)
    {
        // Parent site does not have its own top link bar
        // so use the parent's Quick Launch.
        nodes = parentWeb.Navigation.QuickLaunch;
    }
    else
    {
        // Parent site has its own top link bar,
        // so use it.
        nodes = parentWeb.Navigation.TopNavigationBar;
    }

    // Check for an existing link to the subsite.
    SPNavigationNode node = nodes
        .Cast<SPNavigationNode>()
        .FirstOrDefault(n => n.Url.Equals(childWeb.ServerRelativeUrl));

    // No link, so add one.
    if (node == null)
    { 
        // Create the node.
        node = new SPNavigationNode(childWeb.Title, childWeb.ServerRelativeUrl);

        // Add it to the collection.
        node = nodes.AddAsLast(node);
    }

    childWeb.Dispose();
    parentWeb.Dispose();
}