Randomly show 1 of 5 most recent post in a category

My php knowledge is limited and I’m trying to rotate the main post on the home page from a selection of the five most recent topics in a category.

Most of the plug-ins seem to select (any number) random posts or recent post.

How do I write a query to build an array of 5 most recent post in a category
and then display only one of them at random.