You must have the Multicurrency feature enabled to create bank accounts in different currencies.
When performing a transfer between two accounts, you will need to enter a reporting currency amount.
Navigate to the Money > Bank accounts menu.
Click on the Transfer link.
Enter the amount. If you are transferring from the Multicurrency bank account, enter the amount in the Multicurrency bank account's currency. If you are transferring to the Multicurrency bank account, enter the amount in the appropriate currency of the bank account sending money.
Add a date and description and hit the Transfer money button.
On the explain screen, enter the Reporting currency amount and hit the Confirm transfer button.