Write the next sentence in the following story.

How to check if your computer can have a wifi card
Shut down your pc and remove the power cord and turn the power switch to off.
Open your computer-case.
Note that opening your case may void warranty.
If you still have warranty or you are uncertain your warranty has voided already check this first. If you do not want to void warranty read the tips and then skip to the bottom part of this guide.