Dave,
I don't think you can use opera.If you use firefox,you paste this in the url bar
wget klik.atekon.de/client/install -O -|sh,hit enter and you will have those two files in home directory.The ./klik-cmg-install-root,has to be installed in /etc/fstab as root,read this link http://klik.atekon.de/docs/?page=How%20to%20use
Read this about uninstalling what you have now,and before installing klik client again.
Close actually the procedure is:
1. Open Firefox/Mozilla
2. (Re)install klik client

(Reason: Firefox/Mozilla arbitrarily names its profile folders, so they must be created first in order for klik to know where to write the settings to. You could call that "bad design" if you want.)

Greetings,
probono

Once that is done you go and klik something and a box will open labeled external protocals program and bottom right there are two buttons one is cancel ,you select the other and your cmg file should start to down load,if everything is working the program will open on it's own the first time when the download compltes.Close it and another box will open asking you to make a comment about the program,this is up to you.After you close your browser,there should be a X.cmg icon on your desktop,if your are using KDE,you click that and the program should run.
Now if I have said anything wrong I know someone will correct me.Dennis