Step 1: Head to your Pixels tab in Business Settings to attach your new pixel to the ad account you would like to use for targeting.
Step 2: Go to Audience Manager.
Step 3: Select “Create Audience” and build a “Custom Audience”.
Step 4: Select “Website Traffic”.
Step 5: Select “All website visitors”. For the largest possible audience, change the time period to 180 days.
Step 6 (optional): To retarget partial traffic, enter your site owner’s top-level subdomain (i.e. “.com”) but do not include the prefix (i.e. http, https, or www).
Step 7: Name your audience.
Success! You will now see this new custom audience containing your site owner’s data when setting up the targeting in your ad sets.