I've added a computer to Webroot for protection on my plan and I need to know how to set it up.

Hi Basflys
 
Welcome to the Community Forums.
 
If you have added a device to your subscription then all you need to do is to install WSA on the additional device that you want to protect. You do not state what operating system you are running but please follow the steps below closely in terms of installing WSA on the target system/machine!
 

• Make sure you have a copy of your 20 Character Alphanumeric Keycode! Example: SA69-AAAA-A783-DE78-XXXX
• KEEP the computer online during the install to make sure it works correctly
• Download a Copy Here (Best Buy Subscription PC users click HERE). Let us know if it is the Mac version you need.
• Install with the new installer, entering your Keycode when prompted to do so in the install process
• Let it finish it's install scan
• Reboot/Restart your system

and that should do the job.
 
Hope that helps but if not or you have any further question then please post back.
 
Regards, Baldrick