I need to make space in my office by getting rid of my books. If I want to run a promotion lets say 2 for 1, how do I do that?

You can post your deal in the book bazaar forum.

Usually you would make your offer is a post in the Book Bazaar.

The most common way to do the orders is to have people order the first book from your bookshelf, and then PM you (and/or post in the forum) with the name of the free book they want. You simply include the free one in the package along with the regularly ordered book (and make sure to also remove it from your PBS bookshelf).

It is usually easier to keep track of the orders if you ask people to post in the forum as well as PM you with the free books ... otherwise it is possible for someone to order a book that a previous person wanted for free, etc. Having everyone post in the forum with their selection means that people can see what was already previously requested, and refrain from also ordering it until you can get the free ones removed from your shelf. (or at least, if you have to tell them that it is already gone, they can see that they could have already known that.)

I know the first time I offered a deal, I did not specify that things must be posted in the forums ... and it was harder for me to keep up with the orders, being on the West Coast, so I would get a bunch of conflicting orders very early in the morning and when I got online at 8am (pacific time) .... all the East Coast ladies had already been up for hours and made a bunch of orders that conflicted with each other.

There are other ways of arranging deals but this way is probably the most common in the Bazaar.