I have read the guides but I didn't make a multisig wallet since Blackbank doesn't have a key.
So this is the screen when I'm about to order Blackbank
For the public key, in Electrum I went to Wallet > Master Public Key.
Refund address: One of my receiving addresses
Private Key: Alright so in Electrum I went Wallet > Private Keys > Export, and then saved the file with the keys.
So, can I use any of these private keys to unlock escrow? BB recommends only using each once, is that right? I just want to make sure I'm doing this correctly and not wasting the vendor's time or locking up his funds, thanks for the help!
Technically you can, but you could potentially expose the private key as part of the transaction. If you've already used that public/private key pair then no worries - I'm sure it's fine. But for next time, or for anyone else reading this, it's actually easier and safer to generate a public/private keypair that's not linked to an actual wallet. You can use a site like bitaddress.org to randomly create the public and private keys that you need. You provide the public key to BlackBank (or whoever) and then you keep the private key somewhere safe until the transaction is finished.