If you installed Bitcoin Core addrindex, you just need to:
a) Set counterparty client’s Bitcoin Core (back-end) setting to Bitcoin Core addrindex server’s IP (and remember that you need to allow RPC from the client’s IP address, in Bitcoin Core’s bitcoin.conf - see Bitcoin Core docs for that)
b) Set counterparty client’s counterparty server setting to J-Dog’s public Counterparty Server
counterparty-rpc-connect = public.coindaddy.io
counterparty-rpc-port = 4000 # for mainnet
counterparty-rpc-user = rpc
counterparty-rpc-password = 1234
testnet = 0 # this is not testnet
wallet-name = bitcoincore # Bitcoin Core (no need to change)
wallet-connect = localhost # assuming Bitcoin Core is installed on the same system
wallet-user = rpcUs3r # use value that matches rpcuser in your bitcoin.conf
wallet-password = 1234h4rd2guess # same as rpcpassword in bitcoin.conf
Note that you must not (or should not) use public Bitcoin Server with mainnet, because RPC requests travel in clear. You want to have Bitcoin Core on LAN or VPN and under your exclusive control.
For Counterparty Server it’s mostly OK (from “can someone steal my coins” perspective) because we just use it to look up “stuff” in Counterparty DB, not to operate on wallet, which happens on Bitcoin Core server.
See my write up on that here (but use mainnet if you need mainnet):