You were correct to use "Target by URL", you just need to use wildcards with the smallest possible unique URL segment. For example:
If you have a "Contact Us" page and the page URL is something like: http://yoursite.url/contact-us/
You'll want to use "*contact*" or maybe "*contact-us*" as the target.
If you can give more details about exactly what you're having issues with, I might be able to provide more help.