The good news is that there are some easy solutions to the problem you seem to be experiencing. To confirm; this particular guide is for desktop computers that have built in Bluetooth support. If at any point you or someone else added an external Bluetooth adapter (it's probably a small USB stick sticking out of a USB port somewhere) then follow this guide instead. In case your not sure what a USB Bluetooth adapter looks like, click here.
When you are ready to continue just click the LETS GET STARTED button at the bottom of the page.