How to add an icon to a toolbar button?

I use ExtractIcon function to retrieve a handle (hIcon) to an icon from a specified executable file. My problem is how do I load this hIcon to a toolbar button? Thanks in advance.

Here is what I got:
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HICON hIcon = NULL;
HINSTANCE hInst;
CString strFile = "C:\\Program Files\\Internet Explorer\\Iexplore.exe";
hIcon = ::ExtractIcon(hInst, strFile, 0);