Problems with ShellExecute()

I am trying to open a PDF file when a button is pressed using the ShellExecute() command and am having problems. I first said:

#include "Windows.h"
#include <shellapi.h> 

and then added later on:

private: System::Void btn2_Click(System::Object^  sender, System::EventArgs^  e) {
ShellExecute(NULL, "Open", "C:\\Program Files\\My Prgram\\test1.pdf", NULL, NULL, SW_SHOWNORMAL);
}

And got the following errors:

1>c:\users\raj\documents\visual studio 2010\projects\helloworld\helloworld\Form1.h(109): error C2664: 'ShellExecuteW' : cannot convert parameter 2 from 'const char [5]' to 'LPCWSTR'
1>          Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

Also, I would like the PDF file to be kept in a folder with the executable (.exe) file and the folder in which both these files are in may be moved, how would I define the directory for this?

Thanks.