<img src="http://ghchart.rshah.org/sigdelsanjog" alt="Sanjog Sigdel's Contribution" />
replace the username sigdelsanjog with your github username and the emphasis text inside alt tag alt
You will then see following output:
You can also add a different color instead of the default green one. And this is how you do it. In your image source link you need to append any HEXCombination colour code to generate chart in different colot that you want
<img src="http://ghchart.rshah.org/0040ff/sigdelsanjog" alt="Sanjog Sigel's GitHub Contribution" />
You will than see a blue color in your contribution chart.
Finally link your contribution back to your GitHub Url with a href tag.
<a href="https://github.com/sigdelsanjog">
<img src="http://ghchart.rshah.org/0040ff/sigdelsanjog" alt="Sanjog Sigel's GitHub Contribution" />
</a>
So with this small link viewers can direcly be redirected to your profile.