create a text file to submit as a Sitemap

How do I create a text file to submit as a Sitemap?

Google accepts simple text files that list URLs. As the text files contain only a list of URLs, Google prefers that you use the Sitemap protocol so you can provide additional information about your URLs. The text file must follow these guidelines:

The text file must have one URL per line. The URLs cannot contain embedded new lines.
You must fully specify URLs as Google attempts to crawl them exactly as provided.
Each text file can contain a maximum of 50,000 URLs. If you site includes more than 50,000 URLs, you can separate the list into multiple text files and add each one separately.
The text file must use UTF-8 encoding. You can specify this when you save the file (for instance, in Notepad, this is listed in the Encoding menu of the Save As dialog box).
The text file should contain no information other than the list of URLs.
The text file should contain no header or footer information.
You can name the text file anything you wish. Google recommends giving the file a .txt extension to identify it as a text file (for instance, sitemap.txt).
You should upload the text file to the highest-level directory you want search engines to crawl and make sure that you don't list URLs in the text file that are located in a higher-level directory.
Sample text file entries are shown below.

http://www.example.com/catalog?item=1
http://www.example.com/catalog?item=11
Once you have saved the text file and uploaded it to your web server, add the URL to your Google Sitemaps account.

You must place the completed Sitemap in the highest directory that you would like Google to crawl. Generally, this is the root directory. Google can only accept URLs contained in your Sitemap that are the same directory level or lower. For instance, if you place your Sitemap in www.example.com/foo/, Google will not be able to accept www.example.com/ as a URL in your Sitemap.

If you have access only to subdirectories on the site, place the Sitemap in the highest level directory to which you have access and ensure that the URLs listed in the Sitemap are at that level or lower. For instance, if you place your Sitemap in www.example.com/foo/, Google will be able to accept www.example.com/foo/bar.html.