That's beyond my knowledge of the forums, I'm afraid 
I'd first check for the option in the edit screen of your original post. Might have to ask a mod if you can't find it there. And if not, just leave it up. There's a similar thread posted every couple of weeks. Just make sure to pay attention to the pinned threads in the forum, since they have the rules about this kind of thing 
1 2017-04-28 01:30:19
Re: Bunch of Commons and Uncommons (4 replies, posted in Buying & Selling Cards)
2 2017-04-27 20:45:19
Re: Bunch of Commons and Uncommons (4 replies, posted in Buying & Selling Cards)
Deckbox doesn't have support for this kind of sale. I'd suggest using something like eBay or Craigslist for lots like this.
Remember to sell cards on Deckbox only through their system to protect both buyer and seller.
3 2017-02-16 05:10:46
Re: Underground Sea- Revised For Sale (1 replies, posted in Buying & Selling Cards)
To sell cards on Deckbox, you'll need a sellers account. Check the market forum or send a PM if you need some help on getting one set up. Welcome!
4 2016-09-06 03:06:35
Re: Unlimited Black Lotus (7 replies, posted in Buying & Selling Cards)
You'll have to create a seller account and use the official Deckbox selling system if you'd like to sell cards here. Please refer to this sticky in the forum for more information: https://deckbox.org/forum/viewtopic.php?id=19347