The buyer or seller can either create a transaction, whether or not they are already registered. 

The only information required to create/approve a transaction is the email address of each party.

If it is not already registered, the party creating the transaction will then have to register in order to validate the transaction. 
The same will apply to the other party, in order to approve the transaction.

<-- How does it work?

Do I have to provide personal information? -->