I hope you have gone through Oracle apps 11i Architecture , installation & File system. If you are reading this post without reading Part I which is at http://reddba.blogspot.com/.html then please first go through it first then only you can appreciate this post.
By Now You know Apps Architecture , Installation 11i Apps & you had a glance Filesystem of Oracle Apps Vision Instance (If you don't understand all directories in file system don't worry, It took 2 years for me to understand various directories in Apps 11i)
Next you should try is Start Stop Oracle application 11i Services .
Order of Startup is
First Database Services & then Application Tier Services (Middle Tier)
Order of Shutdown is
First Application Tier Services & then Database.
In order to check How to Start Stop Oracle apps 11i Middle Tier services & where are shutdown / startup script exist check http://reddba.blogspot.com/2009/04/startup-shutdown-apps-services.html
Database & DB Listener startup / shutdown scripts are under $ORACLE_HOME/appsutil/scripts/$CONTEXT_NAME or $ORACLE_HOME/appsutil/scripts/$SID ( depending on your Apps 11i & AD version )
addbctl.sh is used to control database . Start/Stop database
addlnctl.sh is used to control database listener ( Note that database listener is different from Apps listener)
Try starting stopping services or better open startup / shutdown scripts to check what all they are doing (These are shell files & you can open them by any editor like vi in Unix & notepad on windows)