I did not install opera system wide, only under one user. Do I need to set some kind of path or link or something?
If you installed it only for one user (as that user), then it should not be made available to other users, so you are either trying to do the "wrong thing" or I have misunderstood your Q.
If you'd like opera to be available to all users, then install it as root, by using your package manager. Paths and links "will be taken care of"
Otherwise, try calling opera from a script. This is called "Wrapping it up". It's ugly, but often works.
Then make that script executable
chmod +x /path/to/startopera
Then call that script from your "desktop shortcut". Be sure to give the full path
to the /home/M$ISBS/whatever/startopera
script or it will probably fail.
[KDE 3.x handles this effortlessly. Sometimes linux takes three steps forwards, then one step back. Sigh.]