Could I know how to buy things from people and how to sell items without giving our contacts as stated by the RULES . Can someone explain the details to me ?

You can find more information by going to http://forums.singaporemagiccircle.com/index.php?showforum=1

For your information, the information you are looking for is under the topic "Marketplace postings". Here's an extract of it:

Update

There is a change in the usage of Marketplace. To prevent abuse of the marketplace in its various forms, and/or people coming in, post an advertisment in Marketplace and disappear forever, we have changed the permissions for the usage of this area.

The posting of new topics/thread in Marketplace (i.e. the advertising of products for sale (WTS) or requests to buy (WTB)) is limited to

SMC Forumites who has reached "Contributing Forumite" state (currently set at 80 posts).

The replying to topics however remains open to all.

Also, please do NOT

1) Hijack someone else's thread by advertising with follow-up posts because you cannot start a thread yet. That is both bad form and warning inducing.

2) Flood the other sections with meaningless posts or one-liner posts with very little added value (e.g. "That's funny!", "I agree ", "What do you mean?", "Thank you.", etc etc) in order to raise your post counts. If you have some one-liner you have to say or a joke to share, try to add on to it by saying something that contributes to the topic. Try not to leave it just as a single liner.
Spamming will only result in your post counts being reduced by 50% which mean it will take longer for you to reach the post count needed.

3) Post in other sections to sell your items.

And why when I post for more than 2 times , my profile at the side only put 2 posts? Is a reply considered as a post? And really sorry for asking alot of questions .

Posts in non magic sections of the forum are not counted as posts.
Furthermore, if you flood the forum with non-contributing posts, your post count will be reduced by 50%.

And please do not start a new thread on the same topic. The purpose of having a minimum post count in the sale section is to prevent people from abusing it.

The market place is like a privilege for members who have contributed. Please do not post nonsense just to increase post counts. Nonsensical post will be deleted and post counts reduced. Hope this answer your queries.