To add Blog in Magento we just need to get magento connect extension key and follow below step
In admin panel
system>magento connect>Magento connect manager
and then below input type
Paste extension key to install:
need to add this key
http://connect20.magentocommerce.com/community/AW_Blog
there then click on Install button after that need to proceed
Just it you will get a link in admin panel name blog