Right click your explorer icon/program exec.
Select properties
Now, in the top (target) box, add something like this :
%SystemRoot%\explorer.exe /n, /e, C:\
The last portion (C:\) is the one you are looking for.for example, perhaps you want it to show a folder called "Games" which is in a C: drive folder then type
%SystemRoot%\explorer.exe /n, /e, C:\Games