Either run your own node (thus, the localhost reference in the docs) or call a public one...
$ curl -s http://iota.bitfinex.com \
-X POST \
-H 'Content-Type: application/json' \
-H 'X-IOTA-API-Version: 1' \
-d '{"command": "getBalances", "addresses": ["HBBYKAKTILIPVUKFOTSLHGENPTXYBNKXZFQFR9VQFWNBMTQNRVOUKPVPRNBSZVVILMAFBKOTBLGLWLOHQ"], "threshold": 100}' \
| jq
{
"balances": [
"0"
],
"references": [
"BTJRZDCMYEEQBMGKIGZFDFHQWIWTX9UYUFEOLYIHVVWM9HYRZPOZCKRQFNYDLNGTT9KZHGUTGNSNZ9999"
],
"milestoneIndex": 328554,
"duration": 160
}