creating facebook wall post with javascript

You should start here - Google search - facebook like wall post jquery[^] (jQuery is what making this task done so easily)
 
You will many threads discussing the same thing. Take ideas from there and start implementing. You will surely face problems challenges but that will help you learn things better. Moreover this forum is always there to help people who have show that they have tried and have specific issues.
 
Good luck and happy coding!