I learned about Canva through Richard Byrne's blog post - click here for access to his post.
You can scan Canva's 50,000+ templates by selecting find templates (left side above Upgrade). When you find the template you would like simply select it and then select (click on it) one more time. Now you can go in and edit as you see fit (change the text, text color, style, add elements, etc.
One item of note, when you are finished creating and ready to download I had an issue with downloading to PDF the first time. I had to select PDF print and from there on out it worked perfectly.
Embedded below is a 2 minute and 4 second YouTube tutorial I created.