Simply copy and paste your C# code into the textbox and hit the 'Translate' button. Currently, the translator does not handle < script > tags or any other HTML so your C# code must be pure C#. The VB.NET equivalent will be generated in a textbox below the one with your C# code....
The C# to VB.NET Translation tool is not perfect. However, it is the best C# to VB.NET translation tool that I have come across. It's very easy to use. Simply copy and paste your C# code into the textbox and hit the 'Translate' button. Currently, the translator does not handle