With Turbo C 2.01 I tried a simple "Hello, World" program. I started in a different directory from the TC path. I just typed in the path: e.g. C:\Documents and Settings\hkdani\My Documents\cfiles > c:\tc\tc.exe.
I compiled the program and it ran fine. And the PATH environment variable did not include c:\tc. So, I imagine your problem comes from a faulty installation. If it can't find the stdio.h header file, then it may very well be that the stdio.h file is not installed or not installed properly for whatever reason.
Check the sub-directories of your Turbo C installation. See that you have an include directory, and check that you have the stdio.h file inside the include directory.
click options>directories and remove the directory address. That makes it point to default library address from the root folder having tc.exe
And a small suggestion, if ur learning C using turbo C then google "let us C yashwant kanetkar filetype:pdf". I love that book! best to teach C systematically