Can you please clarify a bit abt. the context, the background, and the specific meaning of "scan" ??
If you meant how a program can read an .html file off the internet and scan its HTML tags,etc. to display it in correctly formatted manner (working like a Browser), then it can be very easily done in Visual Basic - the easiest way is to use the Internet Explorer ActiveX control, which allows you to use the IE engine to do that formatting,etc. and displaying. You'll need the WinSock control in addition to connect to the Internet site and download the .html page.
If you meant how a program can read an .html file off your hard drive and the process it to display some information, then it can be done via File Reading functions of Visual Basic - see http://msdn.microsoft.com
for more details.
If your question doesn't fall in the above, please post more information, and we'll try to help out.