You won't upgrade for upgrade pricing but you can purchase the full version of InDesign CS6. This is basically version 8.0 of InDesign. You can find more details at http://www.adobe.com/products/indesign.html. I would recommend also double checking the system requirements to verify that you meet the minimum requirements.
Version numbering and file formats are crucial in InDesign.
Can I update my softward to edit this work?
Unfortunately not from Indesign 2.0. You'll have to urchase Indesign CS6 or join the Adobe Creative Cloud.
File formats in InDesign have radically changed in recent years. From INX in CS4 and earlier to IDML in CS4 and later.
Even CS3 cannot open IDML files without a special interchange file format.
You'll need to get the newer version file exported as an IDML file then opened in CS4 and exported as an Interchange file.
Try posting in the Indesign forum for more detail