Chances are good that it is not there so lets create it and put out startup applications in there:
# nano -w ~/.config/openbox/autostart.sh
In a previous post I described how to install dcompmgr and Avant Window Navigator, lets add this to the file to autotstart at next login:
#!/bin/sh dcompmgr --gl & avant-window-navigator &
Note the &, this is very important, without it the applications will not be started in the background and they will not run properly or at all.
dcompmgr has only a handful of options to choose from, you can view it by typing dcompmgr --help in a terminal.
Safe your work and exit, in nano:
ctrl+o to safe ctrl+x to exit
Make the script executable:
# chmod +x ~/.config/openbox/autostart.sh
Log out and log in again, the services or applications should have automatically started.
If you find something not working, go over your commands again and make sure they are typed correctly, most of the time it is only a simple typo or the & that is left out.