Some students receive devices with stylus pens that can fold into a tablet mode, like so:
If you received your stylus in its box, you may need to unscrew the end cap—where the eraser would be—and insert the battery. Some styluses may not need batteries, but those that do tend to take AAAA (quad-A) batteries.
If your stylus uses a battery, you will need to power it on by pressing and holding the black button on the side of the stylus while holding it near your Chromebook. A pen icon should appear in the bottom right of the screen like in the image above, and the stylus should work the same as touching the screen at this point.
Using the pen icon, you can access a few quick tools and functions, such as taking a screenshot. Your Chromebook also comes with a few pen-optimized apps, such as Kami for notes and assignments, or Google Keep for notes and personal organization.