Guestbook is a straightforward app. 

Use it eg. in a party setting. 

Some variable names are in Finnish - change them if you like.

The images are from CC search with the permission to reuse - most are from Wikimedia Commons. Some, like the lime background, are from pixabay. 

Fork this if you need a guestbook.

I got the basic idea from two sources: Book called 'Express in Action' and Coursera Full-Stack Web Dev Specialization (Muppala). I highly recommend these two if you want to learn this.