After connecting your wallet, you will be directed to the POP! Marketplace, as seen below. On this page you will find all the current MLPs that are live on POP!
To participate in any MLP, simply click on the card. This will direct you to the MLP Marketplace of that particular MLP.
Note: The values shown in the image below are simply for demonstration purposes. In this particular case, there is one POP!/ETH MLP available for farming.