How can I learn which Class to choose?

BenPleysier  wrote I depends entirely on what you want to do For instance, if you want to create styling rules for a button, go to Bootstrap Buttons alerts, go to Bootstrap Alerts backgrounds, go to Bootstrap CSS Helper Classes Reference In fact, if you want to learn Bootstrap, see Bootstrap 3 Tutorial

Thanks for the great links!

osgood_  wrote Its impossible. A normal workflow when using Bootstrap would be to start with a basic template and use the browser inspect tool to inspect an element. That will divulge the name of the class and any ccs attributes associated with that class. If you want to change any of those css attributes you would copy the class to your additional css file and make the changes accordingly. You only need to include the css attributes you want to change, the attrubutes you dont want to change will get their values from the default css file. After some time working with Bootstrap you will start to remember some of the more frequently used classes and become more skilled, hopefully. There might be a list which someone has put together, those who frequently uses Bootstrap might be able to point you in the correct direction if one exists. Its not the workflow l would personally recomend or choose to use but Bootstrap is what it is, lots of developers use it whether l think they are nuts or not.

By browser inspect tool do you mean see what I like on the web and copy it?