Hey, im going to guess that you got the mappings or perhaps what looks like an image.
If thats the case when you create an object in second life, if you go to the object tab there is a drop down option that defaults usually to box, click on that and change to sculpted, you will then see a place to drop that image file.
Usually sculpties come with examples so you can see what sizing they require to look like the shape you want. If they don't its going to be a case of stretching the item you make out on the different axies till you get the shape your after.
Hope this helps