Type Peanuts in the search bar at GoComics.com. It'll take you to a screen with a large image that says Peanuts and one below that that says Peanuts Begins. For strips before 1954 select Peanuts Begins, otherwise click on the image that says Peanuts. On the next screen click the Read Now button. That will take you to a screen with a date you can click on to select years, months and days.
Happy reading.