Manufacturing is a suite of modules, the common ones being: product data management, shop floor control,material planning, capacity planning, forecasting, configurator plus others depending which version of E1 your one. Each module has it specialisms within it.
You really need some guidance from your company the areas/modules you need to concentrate on, and obviously some "playing" so you understand what you are testing. Try using the "help" in E1 as a start. There is a link to JDE doc library: http://www.oracle.com/technology/documentation/jdedarch.html
Hope this helps
