Once you have saved the Sakshum Toolbar File 'SakshumToolbar.xpi' by downloading from here, Follow thesesteps:
Please make sure that you have downloaded the toolbar using firefox only. Using internet explorer will save the file in zip format, which will not work with firefox.
In your firefox browser click File menu and choose Open File option.
Broswe to the location where you saved the file sakshumtoolbar.xpi.
On clicking Ok it will ask you to install it. Click ok and restart firefox.
On restarting the firefox, you should see a new toolbar below your address bar.
You can use this toolbar to search google and help sakshum to help people in need.