Are you still using Opensuse 11.3? I have 11.2 and when I open Yast and go to the search opton for installing software and type in seamonkey, it shows in the repositories. This is a better way to install than downloading from the internet for any distribution, most of the time anyway. This would have more likely resulted in seamonkey being installed in the appropritate directory. I don't have seamonkey installed but I seriously doubt that /home/user/Documents is the standard installation directory.
If you have the standard KDE, you right click the Desktop and choose Creat New, Link to URL or Link to Application.