On PHPMaster.com there's a recent tutorial posted showing you the creation of a simple blog application with MongoDB + PHP. It's a basic overview, so it's mostly about creates and reads, but it does help get things working.

If you want to create a blog using MongoDB and PHP, this article will teach you. [...] The reason I chose to build a blog application is because it is a basic CRUD application and it is very suitable for easing into PHP and MongoDB web development. We will build a plain user interface using Bootstrap with simple textboxes and buttons. A MongoDB database will store all the content.

He starts off by introducing MongoDB and some of the basic concepts around databases, collections and documents as they relate to it. He then moves into the installation process, getting and configuring a simple MongoDB instance running on localhost. He helps you get the MongoDB PECL driver installed for PHP and includes a bit of code to test the connection. Finally, he gets into the blog example itself and includes the full code to get it up and running.