I would suggest first following the steps outlined in the FAQ relating to blank pages or nothing happening: viewtopic.php?f=8&t=2481
You should have two uploadable directories: /files, and /public. /files are for submission files, etc., and should not be directly web-accessible if you can help it.
Then in the config.inc.php>Files section, it asks for "Complete path to directory to store uploaded files". Which I did, and I assume is the directory mentioned above.
Then it has "Path to the directory to store public uploaded files".
Is this referring to the /public folder within /ojs?
Correct on both accounts. On the first count that, on Windows at least, it should be something like "C:\xampp\htdocs\ojs\files". Notice the slashes -- windows uses \ instead of / for directory structure. But if you managed to install the system fine, these should already be filled out for you.
Let me know if you receive anything from turning error reporting on as per the FAQ.