I install SeaMonkey inside my /home directory (have always done it this way) and in order to launch it, I have to go into the file manager and migrate to the directory.
There are a couple ways to get a launcher going for you.
First of all since you installed Seamonkey to your /home directory you will have nothing in /usr/share/applications as suggested above.
I did a similar install and searched for the .desktop extension and did not find any.
So the best thing to probably do is make one.
Open the Adie editor in
Menu--->Accessories-->Adie
enter the following as written except where all caps. There you will use your own username and the name of the file you have Seamonkey in.
[Desktop Entry]
Categories=Application;Network;
Comment=Web browser
Encoding=UTF-8
Exec=/home/YOURUSERNAME/NAME.OF.FILE.SEAMONKEY.IS.IN/seamonkey
GenericName=Internet suite
Icon=/home/ken/NAME.OF.FILE.SEAMONKEY.IS.IN/chrome/icons/default/seamonkey.png
Name=SeaMonkey Browser
StartupNotify=true
Terminal=false
Type=Application
Version=1.0
Change the directory to Desktop
Click File --->Save As and save using the name "seamonkey.desktop