how do I install my renewal disc?

Hi phicor
 
Welcome to the Community Forums.
 
If your renewal is a 'real' renewal, i.e., you have not been provided with a new keycode then there is nothing to install; the additional time purchased via the renewal will just be added to what is currently left on your current subscription, and there is NO need to install WSA again/make use of the CD-based installer.
 
I am suspecting that the above matches your circumstances but just in case that is not the case please read on below.
 
If you renewal is a 'pseudo' renewal, i.e., you have received a new Keycode then again, no need to install the software. In this case you just need to enter the new keycode in your current installation of WSA as follows:
 

 

 
I should point out that if doing the above then you should make sure that you let your current subscription expire as activation of the new keycode will run concurrently with any time left on your existing key code.
 
Hope that helps?
 
Regards, Baldrick