Google Chrome usually updates itself by putting an Update program in your start-up, but sometimes you may need to (or just want to) update it yourself, or just check check for an update, so here's how to do it.
Step 2: Not technically a "step", it'll automatically start updating if a new update is available. If no update is available, you'll see the same message as in Step 4 below.
Step 3: If an update was performed, all you need to do once it's done is click that "Relaunch" button, which will restart Chrome.
Step 4: After Chrome restarts, you can go back to the About screen and it'll tell you "Google Chrome is up to date".