To install:
- Download the plugin file
- Unzip the file into a folder on your hard drive
- Upload the /simple-sitemaps/ folder to /wp-content/plugins/ folder on your site
Note: If you have an older version of the plugin installed in /mu-plugins/ please delete it.
4. Upload sitemaps.php to /wp-content/
5. Download your .htaccess file onto your hard drive
6. Open up your .htaccess file using EditPlus and add the following to your .htaccess under the line that handles uploaded files:
RewriteRule ^(.*/)?sitemap.xml wp-content/sitemap.php [L]
IMPORTANT! Note the order of the new rule in the sample htaccess file:
RewriteEngine On
RewriteBase /
RewriteRule ^index.php$ - [L]
# uploaded files
RewriteRule ^files/(.+) wp-includes/ms-files.php?file=$1 [L]
RewriteRule ^(.*/)?sitemap.xml wp-content/sitemap.php [L]
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule . index.php [L]
7. Save your .htaccess file. Upload your amended .htaccess file to your public_html folder and overwrite your existing file
TIP:
- Check to confirm that the .htaccess file has been overwritten by making sure the last modified date is the same as the file you’ve uploaded.
- Some FTP clients have a hard time overwriting the .htaccess file and/or some servers are configured to not all the FTP client to overwrite the .htaccess file.
If this happens you need to delete the file from the server and then upload the modified file. 
8. Visit Network Admin -> Plugins and Network Activate it there.
How To Use
Simple sitemaps plugin Very simple and yet incredibly effective and lightweight automatic sitemap generator The sitemap generator automatically create sitemaps for every blog, that’ll then be submitted to Google and updated every time a new post is made. You can check that your sitemaps have been created by going to: blog.domain.tld/sitemap.xml 
