If you still want to use IIS go to the "My Computer" icon and make right-click on them,
select "Properties" option on contextual menu and go to the complex tab,
make click on variable button and search in list for "path".
Select the "path" variable and edit them.
Here you can add your own path to the folder where is the dll files needed for IIS.
For example I have this path variable set:
The "ext" folder is full of dll files needed to run different type of databases.
Don't forghet to put ";" between your added path and the rest of the text.
You can add you path in front or back to the rest of text.
I hope you understand my explantion!