I am sure both those manufacturers make good drives and Argos is OK.
You format the drive by plugging it into the back of the B2 into either of the USB sockets (A or C but note which you use!).
Then from the front panel (using the screen and the round knob menu system) go
man menu > settings > Maintenance > Format USB A/C
Obviously with a new drive the "yellow" highlight is nugatory, but if you are using an existing drive this action would erase its old contents!
The B2 may not recognise that your new disk is actually plugged into the USB (A or C) socket, Ignore this and just go ahead as described above). After doing the Format Press and hold in the Play/Stop button until
"Saving" appears on the Front display. Wait until the time re appears then power off the B2.
When you power the B2 on again the USB drive should now be detected by the B2.
Run a "Scan Disk" and after this finishes, press and hold in the Play/Stop button until "Saving" appears on the Front display. Wait until the time re appears (to ensure your new "scan disk" index is saved).
Then from the front screen again go.
main menu > USB menu > Export to C or A
This Export backup can take quite a time, DO NOT interrupt it! you will see when it has finished by the fact that the B2's front red light will stop lashing.
Note your PC will be able to see the content of the USB after you have finished but it may complain that there is an issue with the drive that needs "fixing". Ignore this, DO NOT LET THE PC FIX THE PROBLEM.
Fred