Ahh, you need a way to start nautius without typing "nautilus". Some LXDE experts might need to step in and help with this, because I have barely used LXDE. I'll try to help though.
There is a shortcut creater for LXDE called "lxshortcut", but I just tried it in gnome and kde but it didn't work for me. Maybe it will work for you since you use Lubuntu. I had to install it because it isn't included in Gnome or KDE
If that utility works, great, but if not, keep reading...
On my system there is a nautilus.desktop file located in /usr/share/applications/ . If you have one too, make sure there is a line inside it that says:
The "LXDE;" part I had to add myself because on my desktop it was only created to appear in Gnome. You will need to open your text editor as root to modify the file.
when done editing you might need to run this command to make the shortcut appear in your menu
You can also copy that file to your desktop folder too if you like having a desktop shortcut. You can use this command into the terminal to do that.
Then you need to right click on that file you just created, go to the permissions settings, and change it to an executable file. I'm not very familiar with LXDE but the shortcut should work.
cp /usr/share/applications/nautilus.desktop ~/Desktop/
If you don't have a nautilus.desktop file in your /usr/share/applications/ folder, you can create one yourself.
1 Create a plain file on your desktop.
2 Paste this into it:
3. Make sure the shortcut will work in your LXDE desktop as shown in blue above as I mentioned earlier. You can also change the shortcut's name and icon if you want.
4. save the file as nautilus.desktop
5. right click on the file and make it executable.
That should do it.