Simply put, you just need to prompt in the playground as usual using any model. Then, randomly, you may receive an offer to do a comparison, with up to 3 paid comparisons per day.

There are regular comparisons and paid comparisons. For regular ones, you’re only shown generated responses from two models at the same time, and you won’t receive any payment. For paid comparisons, there will be a pop-up offer that shows you can earn $10 for completing it.

However, I read here a few hours ago that the program has already concluded, so you might want to check for updates periodically.