define Default Product UOM for website (magento)

..but when i try to import
caatalog it says ‘define Default Product UOM for website ‘ i dont know
how to define product UOM on magento or if i am to define it on magento
or openerp.this is a no brainer..but am that ignorant.need someone to define Default Product UOM for website and make sure the import actalog actually..well ‘imports the catalog’