It isn't complicated using WD_Demo. Here's a modified version of the UserTesting function that demonstrates the minimal code required --
 
Func UserTesting()
	; if necessary, you can modify the following function content by replacing, adding any additional function required for testing within this function
	Local $vResult
	$vResult = _WD_Navigate($sSession, 'https://www.msn.com/en-us/weather/maps/temperature/in-Fastov,Kyiv')
	If @error Then Return SetError(@error, @extended, $vResult)
	$vResult = _WD_LoadWait($sSession, 10, Default, Default, $_WD_READYSTATE_Interactive)
	If @error Then Return SetError(@error, @extended, $vResult)
	; Pause to allow page to fully load
    ; You could use _WD_WaitElement here instead
	Sleep(5000)
	$sHTML = _WD_GetSource($sSession)
	If @error Then Return SetError(@error, @extended, $vResult)
	FileWrite(@ScriptDir & "\source.html", $sHTML)
EndFunc   ;==>UserTesting