xequals,
Thanks for your interest in using my plugin ?? I have a few troubleshooting tips you can try:
1. After installing the plugin, make sure it is activated on the Plugins page of the WordPress Dashboard
2. In the Dashboard, go to Settings > Facebook Conversion Pixel and make sure none of the boxes are checked. Checking these boxes disables the plugin on the selected post types, which would stop the fields from appearing.
3. When editing a post, click the Screen Options button in the upper-right corner of the page, and make sure “Facebook Conversion Pixel Code” is checked. If it isn’t, then the plugin’s fields won’t be visible.
I hope those solve the problem. Please let me know if you run into any more trouble. Thanks!