Add better description and install instructions

README.md

@@ -1,19 +1,35 @@
-# A package for performing stellar photometry.
+# A package for transforming stellar photometry
 
+[![Powered by Astropy Badge](http://img.shields.io/badge/powered%20by-AstroPy-orange.svg?style=flat)](http://www.astropy.org) [![GitHub Workflow badge](https://github.com/feder-observatory/stellarphot/workflows/Test/badge.svg?branch=main)](https://github.com/feder-observatory/stellarphot/actions?query=workflow%3ATest)
 
-[![Powered by Astropy Badge](http://img.shields.io/badge/powered%20by-AstroPy-orange.svg?style=flat)](http://www.astropy.org)
++ If you already have aperture photometry for a field, 
+    * calculate relative flux (like [AstroImageJ]()), and/or
+    * calculate calibrated magnitudes by transforming to a catalog (e.g. APASS DR9)
++ If you have calibrated images but haven't done photometry yet, you can do aperture photometry on your images.
 
-[![GitHub Workflow badge](https://github.com/feder-observatory/stellarphot/workflows/Test/badge.svg?branch=main)](https://github.com/feder-observatory/stellarphot/actions?query=workflow%3ATest)
 
+## Installation
 
-This is a package for doing stellar photometry that relies on astropy.
+You can install `stellarphot` with either pip or conda. `conda` is recommended at the moment because of an issue with installing one of the dependencies of `stellarphot` in Python 3.9 or higher
+
+Install with `conda`:
+
+```
+conda install -c conda-forge stellarphot
+```
+
+or install with `pip`:
+
+```
+pip install stellarphot
+```
 
 
 ## License
 
 This project is Copyright (c) Matt Craig and licensed under
 the terms of the BSD 3-Clause license. This package is based upon
-the `Astropy package template <https://github.com/astropy/package-template>`_
+the [Astropy package template](https://github.com/astropy/package-template>)
 which is licensed under the BSD 3-clause licence. See the licenses folder for
 more information.