If you want to target visitors who have visited a specific page of your webpage, you can only do that (at the moment) by writing a cookie when they visit that page, and then setting up and audience to target the visitors with that value.
Let's see the various steps involved.
Create a Deploy
You should create a Deploy for the page you are interested in:
Add Cookie in Custom JS Area
Once the experiment is created, add the cookie code to the Custom JS area. The code would be as simple as this:
document.cookie = "visited_mainpage=true";
Create an A/B Experience
Then create a separate A/B experience with the audience that matches that cookie value: