Add instruction for operating the server

Add some basic commands for working with the server from within `ghci`, which is
helpful when developing.

README.md

@@ -3,6 +3,29 @@
 All of the commands defined herein should be run from the top-level directory of
 this repository (i.e. the directory in which this file exists).
 
+## Server
+
+To create the environment that contains all of this application's dependencies,
+run:
+
+```shell
+$ nix-shell
+```
+
+To run the server interactively, run:
+
+```shell
+$ cd src/
+$ ghci
+```
+
+Now compile and load the server with:
+
+```
+Prelude> :l Main.hs
+*Main> main
+```
+
 ## Database
 
 Create a new database named `db.sqlite3` with: