Google should return a few results for every object, including pieces of code from which you can get ideas. However this is what I can add:

WScript.Shell - Get Wscript's documentation here.

MAPI.Session - If it's identical to MSMAPI.* objects, this example might become useful.

WinHTTP5.1.dll - What you are looking for is "WinHttp.WinHttpRequest.5.1", but keep in mind that this object only exists on some WinXP systems, so don't expect scripts that depend on it to work everywhere. Instead, use "Microsoft.XMLHTTP"