You cannot buy any less known cryptocurrencies directly with fiat currencies like USD or EUROS.Firstly you need to buy Bitcoin or Ethereum from any top crypto exchanges like Changelly, Binance, Coinbase or Tradesatoshi .After buying Bitcoin or Ethereum then you can exchange it (Bitcoin or Ethereum) with for a alt cryptocurrency like Steem.
You can visit top crypto exchanges:
Changelly : https://changelly.com
Binance : https://www.binance.com
Coinbase : https://www.coinbase.com
Tradesatoshi : https://tradesatoshi.com
You can also buy Bitcoin or Ethereum from Changer with Perfect Money(USD). It is easy & automatic & instant.