//the name of the stored proc is TEST1
SqlCommand myCommand = new SqlCommand("TEST1", myConnection);

//Tell the command its a stored procedure, not regular SQL
myCommand.CommandType = CommandType.StoredProcedure;

//Add a parameter to the command
int i=0;
myCommand.Parameters.AddWithValue("@result",i);

//tell it that this parameter is a return value, not a regular inbound parameter
myCommand.Parameters["@result"].Direction = ParameterDirection.ReturnValue;

//now execute
try
{
    myCommand.ExecuteNonQuery();
//nor retrieve the value in the return parameter.
    i = (int)myCommand.Parameters["@result"].Value;