From Jo Querrien

Suppose you have created something, and you want to share it with others.  What is the easiest way to do that?

First, you need to rez a cube (everything starts with that cube, doesn't it?).  The General tab is where you name your box of items (let's say you made a set of snarky T-shirts).  Name it something that others will be able to tell what's in it (like, in this case, "Snarky T-shirts by MyName").  Then ask yourself - do you want this box to look like a plywood cube, or would you rather it look like something else?  If something else, use the Object and Texture tabs to change its look appropriately (note that if you set a cube's Z to 0.05 and its X and Y taper to 0.2, then rotate it 90 degrees on X, it becomes a nice framed square that you can drag a texture into the middle of and color the borders black for a quick vendor).

Once you have your vendor looking the way you want it to look, pack it with the items you want to share (in our example, the snarky T-shirts).  Click the Content tab and drag the items from your inventory into the inventory of the box.  Note that if you are sharing scripts, you will need to set the scripts to not running or put them on a notecard (full permission only for notecards!) before loading them, or they will run in your vendor.

Once your box contains everything you want to share, go back to the General tab. There, you will find the ability to change the box's behavior.  Click to: can be Touch (the default), Buy Object (the one you want here), or Sit on Object (handy for furniture), among other things.  Set it to Buy Object.  Below that, there is a box to check to set the item For Sale (if you do not check this box, nobody can get your stuff).  Once you have checked that box, you can choose to sell a Copy of the vendor (the customer will get your vendor in their inventory, which they will need to unpack), Contents of the vendor (the customer will get a folder in their inventory, with the things you packed in the vendor in the folder), or Original (the customer will get the actual vendor, which will cease to exist inworld).  Original is not usually a good choice, as it means you can only share your box with one person.

The price of the box defaults to some number (which depends on what world you are in, and possibly also what viewer you are using).  If you change that number to 0, people will be able to click your box and "buy" your things for no money.

You can also go to the bottom of the General tab and set your box to Anyone can Copy, which allows people to right click your box and choose "Take Copy", and get your things that way, but it is easier (and less confusing to new players, especially if you remembered to change Click to:  to Buy Object) to set your item for sale for 0.