Help converting VB (with Handles clause) to C#

I tried to convert the code below from VB to C# but I get an error from the online converter about Handles clauses not being supported in C#. Can someone give me a point in the right direction on how to convert? I am still learning C#.

VB CODE:
Protected Sub cmdSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmdSubmit.Click
' See if Session ID exists
_sessionId = IIf(Application("_sessionId") Is Nothing, Application("_sessionId"), "")
_serverUrl = IIf(Application("_serverUrl") Is Nothing, Application("_serverUrl" ...