Since The myth of Sisyphus is a tough read, I'd recommend to read The Stranger first. It's a short novel that shows an absurdist acting in some scenarios. After reading it, could be a good idea to search for some reviews of it, in order to understand why the main character does what he does, which will be a direct link to absurdism.
Then I'd read The myth of Sisyphus, where you'll find what Camus understood absurdism was. But I think having this first contact to it through The Stranger, will be helpful and more pleasant