Lately I’ve decided to build a .NET v4 website…. thus I needed to add the IIS capabilities… after an exhaustive search, I found what I needed thanks to Brad over at StackOverflow:

1. Open your command prompt (Windows + R) and type cmd and press ENTER
   ^{You may need to start this as an administrator if you have UAC enabled.
   To do so, locate the exe (usually you can start typing with Start Menu open), right click and select "Run as Administrator"}
2. Type cd C:\Windows\Microsoft.NET\Framework\v4.0.30319\ and press ENTER.
3. Type aspnet_regiis.exe -ir and press ENTER again.
   • at this point you will see it begin working on installing .NET’s framework in to IIS for you
4. Close the DOS prompt, re-open your start menu and right click Computer and select Manage
5. Expand the left-hand side (Services and Applications) and select Internet Information Services
   • You’ll now have a new applet within the content window exclusively for IIS.
6. Expand out your computer and locate the Application Pools node, and select it. (You should now see ASP.NET v4.0 listed)
7. Expand out your Sites node and locate the site you want to modify (select it)
8. To the right you’ll notice Basic Settings… just below the Edit Site text. Click this, and a new window should appear
9. Select the .NET 4 AppPool using the Select…
10. button and click ok.
11. Restart the site, and you should be good-to-go.

(You can repeat steps 7-on for every site you want to apply .NET 4 on as well).