Add a tag

I would like to add tags via wordpress and it seems like that is supported by your plugin. Can you help with an example?

Here is the code from your plugin:

    function tag_add($params, $post_data)
    {
        $request_url = "{$this->url}&api_action=contact_tag_add&api_output={$this->output}";
        if ($params) {
            $request_url .= "&{$params}";
        }
        $response = $this->curl($request_url, $post_data);
        return $response;
    }

    function tag_remove($params, $post_data)
    {
        $request_url = "{$this->url}&api_action=contact_tag_remove&api_output={$this->output}";
        if ($params) {
            $request_url .= "&{$params}";
        }
        $response = $this->curl($request_url, $post_data);
        return $response;
    }

If I want to add and remove a tag from the current user?