How to start farming in Green-Pool.org
First of all you need to have your node and wallet synced.
Next, you go to "Pool" tab in your chia client. There you click on "Add a plot NFT" button. You will need some funds for that, so if your wallet is empty, you will be presented with an option to get some mojo from chia faucet.
After clicking "ADD XCH FROM THE FAUCET" your browser will open https://faucet.chia.net web page, where you can request some funds by providing your wallet address.
When your funds arrive you will be able to create plotnft. Choose "Connect to pool" and enter https://api.green-pool.org as pool URL (without trailing slash). You will be presented with pool information. Accept by hitting "Create" button.
After creating the plotnft, which might take a while as it has to get propagated over the blockchain, it will be diplayed in "Pools" tab with autogenerated name.
Now you will be able to create plots in the new format. In the Plot creation tab, there is additional step nr 5, where you define the plotnft for which to create plot. Be cautious, if you leave this field set to "None", you will be creating plots in the old format.
After creating plots you will be farming them with Green-Pool.org