add initial answers to questions that were asked

Author: tomeichlersmith

src/SUMMARY.md

@@ -34,6 +34,7 @@
 - [Building and Installing ldmx-sw](developing/building/intro.md)
   - [Shared Computing Clusting](developing/building/clusters.md)
   - [Updating ldmx-sw](developing/building/updating.md)
+- [Framework Structure](developing/framework.md)
 - [Transition to ldmx-sw v4](developing/transition-to-ldmx-sw-v4.md)
 - [Tracking Performance of ldmx-sw](developing/performance.md)
 - [Container-Software Compatibility](developing/compatibility.md)

src/developing/framework.md

@@ -0,0 +1,22 @@
+# ldmx-sw Framework Structure
+
+ldmx-sw is organized into "modules" that contain related code, the `Framework` module
+is of particular importance since it defines the core processing interfaces and handles
+reading/writing data from/to the ROOT files.
+
+## Where is the `main`?
+Many developers, especially those who are more familiar with C++, will want to know
+where the `fire` executable is defined.
+`fire` is defined within `Framework/app/fire.cxx` and this file reveals the overall
+flow of the program.
+
+1. Configure - run the provided Python script and then extract the run configuration
+    from the Python objects that were created when the script was run.
+2. Run - execute the configured run. The `framework::Process` class is the main object
+    that handles the execution.
+
+## How does Python get run?
+We launch Python from within our C++ program by
+[embedding Python](https://docs.python.org/3/extending/embedding.html).
+In the configuration area of `Framework`, you'll see may of these calls to Python's
+C interface (like `Py_InitializeEx()` for example).