I am not that great technically, but I got it done within two hours. You will be guided to a certain degree through the update process. Basically you should follow the instruction here:
http://www.phpwcms-docu.de/dbbackup_en.phtml
http://www.phpwcms-docu.de/dev_1_x_en.phtml
http://phpwcms.de/forum/viewtopic.php?p=35067#35067
http://www.phpwcms.de/forum/viewtopic.php?t=5822
So basically it's:
- backup database
- download you old site to your computer as a backup.
- upload the new version (in a subdirectory if you want first)
- add the filestorage folder with all subfolders to the directory where the new version is (I also added the phpwcms_tmp folder - not sure whether it's needed)
- set permissions for folders and files
- run the setup/index.php file in your browser and follow the onscreen instructions. (On the second screen follow the link "Start here if you want to upgrade...." The second and third link produce update instructions for your database, that you should copy and paste into phpMyadmin - click on the database name, then select the SQL tab, paste the stuff into the textfield and hit 'Go'.)
It's not as scary as you might think, especially if you make sure that you backuped everything before.
Post any questions you might have.