I have download stackapplet from here and PPA from from Here.
I can't follow after this what to do.
I have refered this question but can't follow.
After installation, confirm that you have installed by using:
dpkg -s stackapplet | grep Version
If you get a result you should be able to run the application directly from the dash.
NOTE that you have also to install the python-appindicator package.
sudo apt-get install python-appindicator