How can I make an automatic Picture of the day on my Website?

im pretty new to the html business and im working on a PepeTheFrog website. I would like to have a "PepeOfTheDay" where a random pepe is honored every day. But I have no clue on how to make something like that.Ah and by the way this is for a school project and i have 4 days left to present my website. I would appreciate a detailed answer how to do it what does what and where to put it Thanks in advance