Update README

README.md

@@ -7,5 +7,45 @@ As geophysicists can never agree on a standard colormap to plot seismic datasets
 This package is designed to be minimal initially and try to include as manny cm as possible. 
 Open a pull request for any new colormap that you want me to include and I will put it in the package as soon as possible.
 
- Here is a list of available colormap now:
- - Blue-White-Red (when alpha is 0, it is the default seismic cm)
+## List of Available Colormaps
+- Blue-White-Red 
+- Seismic
+- Phase
+- Frequency
+
+
+![Colormap Demo](/fig/colormaps.png?raw=true "Colormaps")
+
+
+## Dependancy
+- [NumPy](http://www.numpy.org/)
+- [Matplotlib](http://matplotlib.org/)
+
+## Usage
+For a given $CM (replace $CM by the actual colormap that you want to use), you can use it as following:
+```
+from seiscm import $CM 
+import matplotlib.pyplot as plt
+
+plt.imshow(img, cmap=$CM())
+
+```
+
+## Installation
+
+### From PyPI
+```
+pip install seiscm
+```
+
+### From source file
+Download srouce file from [releases page](https://github.com/gatechzhu/SeisCM/releases). Under the root directory, type:
+
+```
+python setup.py install
+```
+
+
+## Contact
+
+In counter of any trouble, contact *gatechzhu@gmail.com*