Messing with other people's code (Well, temporarily. And convincingly.)
One tool that is essential for debugging (fixing code) and coding is a browsers element inspector.
While on this page, press F12, press Ctrl + Shift + I, or right click and click "Inspect Element" in the context menu.
A sidebar/bottom bar should appear with code inside it.
On the top left corner of the element inspector (DevTools from now on), there should be a element picker that looks like a square with a cursor on it. Click on it and click on the blue paragraph below. Double click on the text between <p style="color: #0000FF;"> and </p>. Change the 0 to whatever you want, like 1000000. Cool, huh?
Random Game Website
My Points: 0
Note that this is for the current session only - once you reload the page, everything is back to normal. But think of the possibilities! To close the DevTools, click the × at the top right of the DevTools or use any of the keyboard shortcuts above (I personally use F12 for toggling DevTools).
Explore the code of random websites. It is good to look at examples while learning. Look at the source code of multiple pages of my website.