I believe the best free resource to get started digital painting with Photoshop is Ctrl + Paint. Before watching this magician, Matt Kohr, explain how painting works on Photoshop I thought painting was really out of reach as a hobby. As said in the comments, I really think Corel Painter might be slightly better in terms of imitating the real feel of canvas. If you have a skill set already in Photoshop though, painting is not that difficult to pick up.
To understand how to make brushes that would imitate the above painting you might want to start with this video on Ctrl+Paint and build your way towards researching how to create custom brushes in Photoshop