You should have a min. of 25 posts and a member for atleast 2 weeks to post in Buy Sell And Trade Section. Check This : http://forums.digitalpoint.com/faq.php?faq=dp_faq#faq_posting_guidelines
i usually do try read rules, and i did cus that was the first thing that i thought about. but i coulndt locate it now we all good that i know what i have to do.