All I know is that creators use S3OC and s3pe, but I don't know what steps are taken to create a new pattern using these two tools. Can someone help me, please?

I know how to make terrain paints in TSRW, but I have problems with it too many times--sometimes they'll work, and other times I'll make one, they look fine, and instal fine, but never show up in the game--total waste of time. I want to learn how to use something other than TSRW. >_<

First you need to clone a terrain paint in Sims 3 Object Cloner (S3OC) and then you open Sims 3 Package Editor (S3PE). Then click file->open and open it. Next you find the _IMG file and export it somewhere you can find it. You open the file in some picture editing program that can open .dds files. I use paint.net.
Hope this helps!