If you're writing your ASP.NET server-side code in VB, then it's standard VB.NET code just like you're accustomed to. The two most popular languages for .NET are VB and C#, and you can use whichever you wish. But the fact that you're using ASP.NET doesn't change the syntax or structure of either one of them.
Basically, ASP.NET is a web framework that you'd be using to build web applications written in your language of choice (in this case, VB.NET). You'll want to know more about the framework, such as how to design your forms and make use of the web controls (and knowing HTML/CSS/JavaScript is a big help too). But the overall syntax of the VB code doesn't change.