Update README

README.md

@@ -6,3 +6,43 @@ This is a generalized Exposure Time Calculator for imaging and spectroscopic ins
 * various optical glasses (BK7, CaF2, FK5, fused silica etc)
 * sky background/atmospheric emission data
 * filter transmissions for LCO and selected ones from ESO, ING, Gemini, SOAR
+
+## Usage
+
+## Development Guide - Getting started
+
+Before installing any dependencies or writing code, it's a great idea to create a
+virtual environment. We primarily use regular `virtualenv`s to manage virtual
+environments, although `conda` *may* work. Using virtualenv, you can run the
+following to create and activate a new environment:
+
+```
+>> python -m venv /path/to/new/virtual/environment
+>> source /path/to/new/virtual/environment/bin/activate
+```
+
+(On Windows, invoke the venv command as follows:
+
+```
+>> C:\>Python310\python -m venv C:\path\to\myenv
+>> C:\> C:\path\to\myenv\Scripts\activate.bat (cmd.exe)
+or
+>> PS C:\> C:\path\to\myenv\Scripts\Activate.ps1 (PowerShell)
+```)
+
+If you have conda installed locally, you can run the following to
+create and activate a new environment.
+
+```
+>> conda create env -n <env_name> python=3.10
+>> conda activate <env_name>
+```
+
+Once you have created a new environment, you can install this project for local
+development using the following commands:
+
+```
+>> pip install -e .
+>> pip install -e .'[dev]'
+>> pre-commit install
+```