Can someone please me import xcp in to a wallet?

I am new to counterparty and have some xcp on an exchange. I just want to take my xcp off the exchange so I have control of the xcp.

I have an ubuntu livecd and want to backup to a USB drive. Is there a simple and secure way to do it?

And one more thing, does the passphrase have to be 12 words, or can it just be something like a long string of ASCII characters? Thanks.