1) Backup
2) Upload/extract new 1.9.1 code
3) browse to tiki-install.php
4) login as admin
5) Choose the 1.8 to 1.9 upgrade script
6) remove tiki-install.php
7) Have a cuppa tea and relax
Easy 😊
So easy in fact Ill put the kettle on now in readyness 😊