Well, there is no clue here as to which Windows version or which OE version, which is not much help, but here goes with a wild stab.
OE/Files/Import/Messages/ then select the version of OE you WERE using.
'Next'
Click the button 'Import mail from a OE xxx ....'
'Ok'
Browse to the folder you found elsewhere - no need to 'bring' it to your desktop
'Next'
Select the folders you wish to import.
Bingo