Add the following to your yaml config:

ShopGoogleAnalytics:
  web_property_id: UA-XXXXXX-X

Some additional configuration options (all on the ShopGoogleAnalytics object):

• disable_on_dev - by default analytics code is not included unless Director::isLive() is true, setting this to false causes it to show up any time
• no_sku_prefix - if an item doesn't have a SKU/InternalItemID set we need to send something to google using this prefix and the ID
• disable_pageviews - don't include the basic pageview code. set this to true if using another analytics module such as silverstripe/googleanalytics
• use_requirements - default is true, which uses Requirements::customScript to insert the tracking code. Set this to false and add $GoogleAnalyticsJS to your template to have more control over where the code goes.
• tracking_type - 'Universal' or 'Classic' - default is Classic to maintain backwards compatibility
• tracking_code - allows finer grained control over the templates used to generate the javascript

• Optionally allow recording actions: add to cart, remove, set quantity.
• Integrate analtyics reporting into CMS for an order. This way site owners an see additional info for the customer.