1. In your FTP (I use FireFTP) rightclick in the server window (in the root folder of your WP installation) -> Create File
2. Write inn sitemap.xml
3. Do the same with sitemap.xml.gz
4. CHMOD it to 666 (right click on the files -> Properties -> 0666
Tried the 0.73 in WP 2.6.1 and got this message under Design -> Tabbed Widgets
Warning: Invalid argument supplied for foreach() in /mounted-storage/home21a/sub002/sc20921-AMCE/www/wpstart/wp-content/plugins/tabbed-widgets/tabbed-widgets.php on line 533
Parse error: syntax error, unexpected T_STRING, expecting T_OLD_FUNCTION or T_FUNCTION or T_VAR or ‘}’ in /mounted-storage/home21a/sub002/sc20921-AMCE/www/asphaug/wp-content/plugins/umapper/Umapper.php on line 27