On the next screen fill in the values written in CAPITALs:

[BLOCKCHAIN]
# options: bitcoin-rpc, regtest
blockchain_source = bitcoin-rpc
network = mainnet
rpc_host = LAN_IP_ADDRESS or HIDDEN_SERVICE_ADDRESS_FOR_BITCOIN8832.onion
rpc_port = 8332
rpc_user = RPC_USERNAME_OF_THE_CONNECTED_NODE (as in the bitcoin.conf)
rpc_password = RPC_PASSWORD_OF_THE_CONNECTED_NODE (as in the bitcoin.conf)
rpc_wallet = LEAVE EMPTY or fill the wallet name specified in bitcoin.conf


More info on how to prepare a remote node to accept the JoinMarket connection:
https://github.com/openoms/joininbox/blob/master/prepare_remote_node.md