simply create a .desktop file and put in
/usr/local/share/applications
or
home/USERNAME/usr/local/share/applications
For example, using midori:
#!/usr/bin/env xdg-open
[Desktop Entry]
Name=NAME OF WEB-APP
Exec=midori --
app=http://ADDRESS OF WEB-APP
Terminal=false
Icon=PATH TO ICON
Type=Application
Categories=Network;WebBrowser;
To use other web browser, simply replace the executable name. Is that right?