1. Log in to your Order Management System. Go to Settings > Policies, Addenda, and Disclaimers. Enter your Google Analytics Tracking code if it's not already there, and your Google Analytics Domain.
2. Click Layout and create a staging layout from live layout values (you need to archive and then delete the current staging layout if one exists, and I always recommend archiving the live layout first as well).
3. Edit the staging layout with your experiment - this will be the experimental layout.
4. Cross browser test your staging layout. When you are happy with it, archive it and name it.
5. Log in to Google Analytics, select Behavior > Experiments, and click Start Experimenting.
6. Name your Experiment Experiment 1, set a goal (Perhaps Page Views, revenue or goal conversions), a percentage of traffic, and email notifications (we recommend On), and click Next Step.
7. Enter the URL of any page of your live store, name the page Live Layout, and check "Consolidate experiment for other content reports."
8. For Variation 1, change the select box from http:// to relative, then paste in the query string of your experimental layout. Do not enter the full URL. Name this variation version2, then click Next Step.
9. Copy your Experiment Code in Step 3 to your clipboard. Paste it into your HTML editor, then paste the following directly below the first comment:
10. Replace "yourdomain.com" with your Google Analytics Domain set in the OMS.
11. In the OMS, toggle to your live layout, Edit the Advanced Layout, add your revised Experiment Code to the top of the Head Addendum, and click Finish.
12. Click Next Step in Google Analytics. Confirm that it validates and click Start Experiment.
13. Visit your store in multiple browsers using the forced reset URL (http://www.nexternal.com/agile/?Reset=True&Staging=False). If you use at least three browsers, then you will probably see at least one instance of each of your two store variations. If not, clear your cookies in one browser and revisit the site, clearing your cookies each time, until you see the both versions. If you don't see both versions after clearing your cookies several times, then there is probably an issue.
14. Check on your experiment in Google Analytics daily and use the results to refine your store.
FYI, it takes time for the experiment results to populate. So set it up, and then check on it the next day.