We are developing a web application program which will automatically send email reminder through Marketo.
I try to look for VB.NET API, please provide me the info, I cannot locate it from the support platform.
There is no such thing as a a VB API. The code examples are just way to do it in each language, but at the end of the day, you call a remote REST web service and pass parameters.
For example, you can send emails via Request Campaign » Marketo Developers
And this page includes sample C#.NET code.
I think you can translate C# to VB.NET easily.
Of course you can create scratch codes using httpRequest class easily.