I dont know what it looks like from a VB.Net perspective, but in c# I would do :-
Columns = { "Field1", "Field2", "Field3" }
as in
using (var conn = new MySqlConnection(connectionString))
{
var bl = new MySqlBulkLoader(conn)
{
TableName = "tblquestions",
Timeout = 600,
FieldTerminator = ",",
LineTerminator = "\r\n",
FileName = path,
NumberOfLinesToSkip = 1,
Columns = { "Field1", "Field2", "Field3" }
};
var numberOfInsertedRows = bl.Load();
}