Have you googled? Here is the first link google gave to me:
http://www.developerfusion.com/tools/convert/vb-to-csharp/[
^]
These converters are able to convert most of the VB.Net code, but there are some cases where it is simply not possible and you need to do it manually.
For your VB.NET code, the correct C# code would be:
if (!Page.IsPostBack)
BindGrid();