How to post on the users FB wall right after registration?

Hello,

I am pleased to meet you and i am writing this to you on behalf of my client Curtis.

The WP plugin "Ultimate Facebook" has been successfully installed at client website recipeslam.com, its working fine.
Here we have a requirement, we would like to post on the users FB wall right after registration with website through Facebook. please guide me to accomplish this ASAP.

please do let me know, if any information from our end.