Error msg in Web.config: Child nodes not allowed.

i had to install the CMS insitecreation software but i got this error , i had VS 2005 installed but it shows that this will not run at 2.0 compiler .

i must have to install the 3.5 version to run this CMS insitecreation

look at this line in web.config ..
providerOption name="CompilerVersion" value="v3.5"
this is creating problem , i must install now the v3.5 to work with this website project .