Show all posts from a specific author

I don't know why I can't figure this out, it should be simple (hopefully, it's because it's 1.30am, not that I've gone mad).

How can I show a list of posts from a specific author? I have a site where there will be two people writing separate posts, and I need to be able to show all the posts from each of them separately.

I just can't seem to figure out how to do it :disappointed: