A few things to keep in mind...
1) Depending on how the VB.Net code was written, automatic conversion may or may not be 100% possible. VB.Net allows a "looser" coding style that would be ambiguous to C#. So, some manual intervention may be needed.
2) If the VB.Net code functions correctly, you may want to just leave it as VB.Net. Both VB.Net and C# projects can co-exist within the same solution.