Go to: Google Adwords
There is no immediate need to enter your credit card information or even advertise with the platform, we will simply be setting up a script using Adwords that attaches a cookie to visitors who land on your website. This will allow us advertise across the Google Display Network to past visitors to the site if you decide to down the road.
Step 1: Create an Account
Step 2: From the "Campaigns" Tab, click "Shared Library" form the left pane.
Step 3: In the Audience Box, click "view"
Step 4: Click Create New Audience, select Remarketing List
Step 5: Select - Define a list of site visitors by placing a new tag on selected pages (previous version of remarketing)
> Membership Duration "90" Days
> Name: Website Visitors
Step 6: Save your Remarketing List
Step 7: Once on your remarketing list home, click [tag] and a script will appear.
Step 8: Insert this script on every page of your website right before the tag