Another in the long line of mexopts.bat questions

First consider me an absolute dummy about Simulink compilers. I want to use the Embedded Matlab Function block. I keep getting mexopts.bat not found errors. Nothing I've read about this topic makes sense to me. Please answer the following questions:

1. Where do I find the folder that contains the included compilers for the installed Matlab2010b? I'm not sure what came with my copy. The list of compatible compilers on the Mathworks site doesn't help. 2. If Matlab comes with a default compiler, why doesn't it work automatically? I'm happy to use the default compiler at this point. 3. If I use mex -setup, how do I know which compiler is the default compiler? 4. How is this mexopts.bat file written? Do I create it with a text editor? Where should the file be located?

Thank you.