Welcome to Openbox ! !
But you might enjoy several other ways which are already setup defined and pre configured in the distro.
First, you will want to visit the directory /home/you/.config/openbox and take a look at the autostart.sh file. There, you will find comments (starting lines with a #) that will guide you.
So you have 2 ways to setup the background, already inside : with the feh command lines, just add the path to the wallpaper directory of your choice, or add the wallpapers of your choice to the directory already setup. feh offers 2 default choices and more choices you can discover later, but no icons on the desktop.
The second method is with the pcmanfm preferences : in the Openbox right-click menu on the desktop, go down to the menu Preferences > Desktop Prefs, this will open the pcmanfm preferences window where you can setup the default background of your choice.
if you choose pcmanfm for managing the desktop (in autostart.sh in the ~/.config/openbox directory), you will have all icons on the desktop that you can wish.
You can have the files and directories show if you put some there, and you can copy *.desktop files from /usr/share/applications, or even right-click in the app's menu entries in the lxpanel menu, and will have a choice to "add to the desktop".
The last way to configure icons on desktop is with iDesk, but not very easy as the program is out of age. I have done that for a "KDE/Openbox Chrismas" version I did for fun. Here is the result:
For some parts you have done well. For transparency, just hit the Openbox right-click menu : go down to Preferences then to "Transparency", or "Transparency, fadings", or "Transparency, fadings, shadows". It will set and unset xcompmgr-dana (should be in /usr/local/bin) in different ways.
For even more fun, I recommand you to read PCLinuxOS Mag Openbox Special Edition, available here : http://www.pclosmag.com/
PS: I have also made available a new set of configuration files, you can get them at this thread : Openbox : updated configuration files New New !