How to sell

I have create some boxed stuff ,and now i want they sell but don't know what can i do. There are free spaces for this and i can sell for unlimited times? Now i have just 1 box and if i want sell for example 100 boxes i must create 100 boxes or there is another method?
Thank you and sorry for a silly question.

You need to set the objects to sell a copy, not the original, then you can sell infinite numbers of the same object.

Make sure you check all your permissions, you don't want your creations copied and transfered by everyone. You need to either make them copyable or transfer, not both.

Ok but is possible to select "infinite" times or is an automatic thing? thank you

When you set something to sell copies, you can sell it as many times as someone else is willing to buy it.

For free places to sell stuff, search for free yard sales. Otherwise, you can also search for cheap vendor spaces. Some vendor spaces go for a little as L$25 per week for a respectable number of prims (usually less than 25, for that bargain price).