In the HTML portion of the page, make at least 5 divs. Give them all a unique ID.
Using CSS, set the size of the divs. Make the width as long as the page, and choose a height. (Hint: can you find a way to make the computer detect the width of the page?)
Set the background color of each div. Wether you want to make a rainbow, use only neon colors, make a color palette sample... It's up to you!
Keep working on your project until you're happy with it. Be creative and have fun!