Counterwallet generates addresses based off a 12-word passphrase, and does not currently allow you to import your private keys.
You might want to try using freewallet.io to generate a wallet, as it allows you to import your private keys and just use the address.
You register to a coin exchange like bittrex or poloniex which trade bitcoin for XCP. Then send bitcoin to the exchange and trade for XCP. Then you can send XCP to counterwallet.
You will also need some bitcoin sent to counterwallet for transaction fees inside counterwallet. Counterwallet can hold bitcoin, XCP and all tokens in one address. But be sure to send coins from counterwallet to a coin exchange to the deposit address for the coin type only.