Using the land edit tool

okay I am with the owner of my land trying to figure out how the ratios for grass/sand/water etc work. How do I adjust the numbers so that at one level I have sand, raise it for grass?

Hi! Welcome to the fun of estate management!

First, the only people who can control the terrain textures are the sim owner on a private island, or their estate manager(s). If you own mainland property, or if you have a parcel on a private sim but do not own or manage the sim, the it is impossible to adjust the actual terrain textures. Your only option, if you control less than the entire sim as a private sim, is covering the actual terrain with prims that are colored to look like terrain.

If you are the owner of the sim, or their estate manager, the estate management tools allow you to control the terrain textures only on a whole-sim basis. There is no parcel-level control. There is a tab on the estate tools that has eight texture panes, with altitude levels below that for each corner of the sim. That is where this is controlled.

In short, an estate manager or sim owner has limited control over land texturing, sim-wide. You apply four pairs of textures to four altitude-restricted bands, and can adjust the limits of those bands somewhat at each corner of the sim. What you apply is a low rez 128 x 128 base version and a high rez 512 x 512 main version of each of the four textures. Then the SL client 'paints' that terrain based on altitude, blending the tiled textures at each border. With effort, you can do things like having coral sea-bottoms, white sandy beaches, green hills, and rocky ridges and mountain peaks. By adjusting the height limits at the sim corners, one area may have sandy beaches, with rock higher up, while another has rocky coastlines, and the sand is all below the water level. But there is no fine control on a per-parcel basis.

If you look in the Library section of your inventory, there is a folder in there with terrain textures in it. You can use those, or you can create your own, with the same resolution size pairings as the base and high-rez versions of one of the library pairs. Both textures must be seamless and tilable.

(Note: I am not on a system right now that has access to SL. When I get time later tonight and can go in-world, I'll try to clarify the details a bit more.)