How to draw with CSS canvas a slideshow frame?

I have 2 slideshows which should look like this. The user will upload the photos via a Wordpress gallery so I can't cut them up to make them transparent (plus I don'开发者_运维知识库t really know how). I've already posted a question here on how I may achieve this and one user was kind enough to tell me that I have 2 options: webkit mask and canvas; canvas being the recommended option because of better browser support.

For the past hour I've been searching on the Internet on how to draw with canvas but I've had no luck...

Could you please direct me to a tutorial that's easy to follow or give me some pointers?

Thank you!!

I would recommend MDN's docs on the subject.

There are also some good resources in a similar question.

Definetely MDN's docs are better adopted to that activity, however if you want to get some valuable pieces of advice you can go and visit this website http://www.canvascolour.co.uk/ Ask them your question they may be able to give you the right solution.

;)