by Ange Tuteur August 4th 2013, 8:54 pm
Navigate to..
Admin Panel > Modules > Points and Reputation > Reputation
Tick 'yes' for Activate "Thanks" button and save. You can modify the rep received from thanks by clicking the reputation management tab.
Be sure you have a thanks image as well so it will show up for thread starters, to add that image go to..
Display > Pictures and Colors > Pics management > Advanced
Click the buttons tab and scroll down to thanks button, then specify your image source. Please remember that the thanks button will show up for topic starters only.
Good luck.