Login into your Magento administration panel, click System ⇒ Magento Connect ⇒ Magento Connect Manager
. Next go to http://connect.magentocommerce.com/ and search for "Provide Live Help" module. Get the "Extension Key" and paste it into your Magento Connect Manager
, click Install button
.

Download module here, decompress it and upload module files to the web server - see README.txt for details.
In Magento administration panel select System ⇒ Cache Management
, click Flush Magento Cache button
and Log Out link 

Login into your Provide Live Help Control Panel and click
link in "My Account" panel. If you don't have an account yet, you can register
for free here. Now right click and copy into a clipboard the HTML code of live chat button. See
in the figure below.

Login back into your Magento administration panel, click System ⇒ Configuration and select Live Support Chat Settings
in the left sidebar. Paste HTML button code into field
and click Save Config button
.

Make sure Provide Live Help chat application is running and verify there is a green icon
in your taskbar which indicates the application is connected. Open your Magento store in a web browser and click live chat button to start a chat session.