There are 7 total challenges that increase with difficulty. Inside each challenge there is a html, css, and js file. You shouldn't have to edit the css file however you're free to add classes/ids to things (if necessary) in the html file. Each js file has some boilerplate code to get you started! Good luck!
The final 2 challenges (5/6) are optional stretch goals!
Here's a reference for commonly used methods:
document.createElement("name of element") //create's a new element
document.getElementById() // This grabs the element by the id. You can also use get element by classname/name/tag however they return an array.
element.style // use this to change style properties
element.innerHTML // changes the inner html of a element.
Additional reference Dom methods;