Mary I will try explaining this again. You do not at any point hand edit config files. These are the installation instructions PhotoPost PHP Photo Sharing Photo Gallery Installation Guide
Basically you are entering the wrong information which is your issue. You need to simply upload the files set file and directory permissions as noted and run the install script. On the install script you would enter the correct database info for classifieds and the one for vb
where asked. Now on step 4 where your posting screen shots you enter your forum information. You seem to be entering your classifieds table prefix etc where we are asking you what your forum mysql table prefix is.
You will not have a successful install until such time as you enter the correct information. Your vbulletin mysql table prefix is not pp_. When I say to check for the correct vbulletin information in your vb
config.php file that is located in your forums includes directory. You can not get that information from your classifieds config-inc.php file which you seem to keep bringing up here and the heart of your issue.