VB.NET vs. PHP or ASP

I am a new user to VB.NET, and I am unfamiliar with PHP and ASP, I was wondering if I know VB.NET, can I do all the same stuff that I could do with PHP and ASP? Basically, I just want to know if I would still need to learn PHP and ASP. My interest are in web design, which is why I am trying to learn all of this stuff. Thanks for any and all help.