Can't fine cl.exe

I’m using windows seven 64 bit, I have installed visual studio 10.0 and CUDA software, SDK and driver.
I know the path of cl.exe, but I don’t know how to add it.So if I try compiling a .cun file it says :
“cannot find compiler cl.exe in PATH”
I have tried editing environment variables, adding a value which contains the path of cl.exe, named PATH.But with no results.
So I would know how is possibile to “tell to the compiler” the path of cl.exe.