Giant List of Heroku Resources
To get started, really all you need to do is sign up for a free heroku.com account and push your apps there.
Hands-on Tutorial (Trailhead): https://developer.salesforce.com/trailhead/search?keywords=heroku
Heroku Cheatsheet: Heroku CheatSheet
How to get started with Heroku: https://devcenter.heroku.com/start
Check out Heroku Buttons ( https://buttons.heroku.com/). You can deploy a blogging platform like Ghost (a spin off from WordPress) on Heroku, with the click of one button from the Heroku Buttons Gallery. Or you can choose other Add-Ons from https://addons.heroku.com/
If you are creating mobile apps, then check out Heroku CX Patterns ( https://www.heroku.com/cx) which provides pre-built templates for mobile apps you can use to fast track your development.
Heroku Forums ( https://discussion.heroku.com/), Heroku Google Group ( https://groups.google.com/forum/#!forum/heroku) and StackExchange ( http://stackoverflow.com/questions/tagged/heroku) have very engaged and thriving Heroku user communities.
“How to Migrate Your PHP Application to Heroku” is a quick and easy overview of the key steps in going to Heroku Cloud: http://www.wizard.codes/migrating-legacy-php-apps-to-heroku/
Hot & Heavy List of Heroku Development Resources: expeditedssl.com/pages/the-hot-and-heavy-list-of-heroku-development-resources
How Heroku works