Things to cover for beginners:
React.createClass – The way in which you create a new component.
render (method) – What we would like our HTML Template to look like.
React.render – Renders a React component to a DOM node.
state – The internal data store (object) of a component.
getInitialState – The way in which you set the initial state of a component.
setState – A helper method for altering the state of a component.
props – The data which is passed to the child component from the parent component.
propTypes – Allows you to control the presence, or types of certain props passed to the child component.
getDefaultProps – Allows you to set default props for your component.
componentWillMount – Fired before the component will mount
componentDidMount – Fired after the component mounted
componentWillReceiveProps – Fired whenever there is a change to props
componentWillUnmount – Fired before the component will unmount
I have covered all these concepts in my lessons here