With the latest forum v3.0 update, there were several changes made to the forum, as well as some new features. One of the largest additions is the "Shop" feature, which allows forum users to buy and sell various things that are offered at the shop and have them displayed in their profile.
To get started, click on the Shop icon on the far right side of the forum navigation bar:
Once you do that, it will look like it is loading your Profile page, but within 5 seconds of loading, a new window should pop up, saying that it is re-directing to the shop:
When the re-direction bar is complete, it will show your Profile options page, but within 5-10 seconds, the Shop menu should show up:
Here, you can choose an item to purchase from the list. All things that can be purchased will have a "Buy" button that is available to click. If it is greyed out, that means you already have the item, or it is currently not available. You can also sell any existing items you have by pressing the "Sell" button to earn back some zeny.
Please note that you can only purchase one of each item; multiple purchases of a single item is not possible. Also, there is currently a limit of 7 items per person, but this item limit may be increased in the near future.
Once you buy an item, your Profile page will be displayed, along with your purchased items:
All your purchased items will also be displayed in your mini-profile bar:
With all this zeny available, you can also donate zeny to other forum members. To do this, click the "Send Donation" link under their amount of zeny:
This will redirect you to a small window where you can list the amount of zeny you want to send, along with a message:
That's pretty much there is to using the Shop feature.
As to earning zeny, each post you make you earn 10,000 zeny. Remember, all posts in the SPAM section DO NOT INCREASE your post count, hence they do not increase your zeny either. Also, don't spam outside of the SPAM board just to make zeny. If I see this going on, you may find yourself with a lot less zeny. 
Although there is a small collection of weapons at the moment, I plan on adding many more things to buy, such as armor, cards, items, etc. Some of these future additions (rare weapons, rare armor, cards, etc.) will be very expensive, so be prepared to "break the bank" when that happens.
I will post all the latest item shop additions in this thread. The Shop feature should now be fully compatible with Internet Explorer 6/7 and Mozilla Firefox 2. If you have any comments or issues with the Shop feature, feel free to post them in this thread.
As for more items, I will be adding Katars and some other things to the shop later today, so check back here later.