I dwell on it in my Blender project class(es) at Builders Brewery (back soon really) so If you want more detail on what LODS are or methods of face reduction, see me there.
Each of the rabbit models shown will be exported from Blender as an individual collada file with a name that indicates which LOD that model is intended to represent. So the upload process is a matter of NOT choosing the "Generate" button and instead selecting "Load from file" on each drop down and then browsing to the relevant collada.
I hope this quick look at some screen captures from the rabbit sculpture helps to demystify the process. Please do not think you must copy this exactly, figure out the math I used for the reductions or take what I am showing as a prescription for every mesh. Even I do not follow exactly the same process each time, since each mesh is different. But this is a good example of how to take a low poly medium sized object and get great Land Imact (1 LI), optimal physics and good LODS with NO loss of detail or quality in the finished mesh.
If you are brand new to making mesh for SL, you should look for as many examples of how to optimize and possibly retopologise higher poly meshes as you can find.
And if you are so new to making or buying mesh you have confused High Poly with High Quality or using Higher LODs than you need as a quick route to a perceived high quality mesh, well then you ARE just confused. But maybe this will help you get over it.
