protected void Button1_Click(object sender, EventArgs e)
    {
        localhost.Vremenno wsVremenno = new localhost.Vremenno();
        string a = System.Convert.ToString(TextBox1.Text);
        string b = System.Convert.ToString(TextBox2.Text);
        Label5.Text = wsVremenno.Sum(a,b);
        Label5.Visible = true;
     }

[WebMethod]
    public string Sum(string a, string b)
    { 
        string c;
        return c = a + b;
    }

using System;
using System.Data;
using System.Data.OleDb;
using System.IO;

namespace DbfHelpers
{
    /// <summary>
    /// Работа с Dbf-файлом
    /// </summary>
    public class DbfReader : IDisposable
    {
        /// <summary>
        /// Путь к файлу
        /// </summary>
        public string LocalPath { get; private set; }
        /// <summary>
        /// Имя файла
        /// </summary>
        public string LocalFile { get; private set; }
        /// <summary>
        /// Соединение
        /// </summary>
        public OleDbConnection LocalConnection { get; private set; }

        /// <summary>
        /// Строка соединения
        /// </summary>
        public string ConnectionString
        {
            get
            {
                string connectionString = string.Format(
                    "Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Persist Security Info=False;Extended Properties=dBASE IV;",
                    LocalPath
                );
                return connectionString;
            }
        }

        /// <summary>
        /// Конструктор
        /// </summary>
        private DbfReader()
        {

        }

        /// <summary>
        /// Конструктор
        /// </summary>
        /// <param name="fileName"></param>
        public DbfReader(string fileName)
        {
            LocalPath = Path.GetDirectoryName(fileName);
            LocalFile = Path.GetFileName(fileName);
            LocalConnection = new OleDbConnection(ConnectionString);
        }

        /// <summary>
        /// Выполнить SQL-запрос
        /// </summary>
        /// <param name="sql"></param>
        public void ExecuteSql(string sql)
        {
            if (LocalConnection.State != ConnectionState.Open)
            {
                LocalConnection.Open();
            }
            var command = LocalConnection.CreateCommand();
            command.CommandText = sql;
            command.ExecuteScalar();
        }

        /// <summary>
        /// Открыть соединение
        /// </summary>
        public void ConnectionOpen()
        {
            LocalConnection.Open();
        }

        /// <summary>
        /// Закрыть соединение
        /// </summary>
        public void ConnectionClose()
        {
            LocalConnection.Close();
        }

        /// <summary>
        /// Выполнить SQL-запрос с форматированием string.Format
        /// </summary>
        /// <param name="sql"></param>
        /// <param name="obj"></param>
        public void ExecuteSql(string sql, params object[] obj)
        {
            ExecuteSql(string.Format(sql, obj));
        }

        /// <summary>
        /// Прочитать данные
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public DataTable Read(string sql)
        {
            if (LocalConnection.State != ConnectionState.Open)
            {
                LocalConnection.Open();
            }

            var table = new DataTable();

            using (var adapter = new OleDbDataAdapter())
            {
                var command = LocalConnection.CreateCommand();
                command.CommandText = sql;
                adapter.SelectCommand = command;
                adapter.Fill(table);
            }

            return table;
        }

        /// <summary>
        /// Прочитать данные с форматированием string.Format
        /// </summary>
        /// <param name="sql"></param>
        /// <param name="obj"></param>
        /// <returns></returns>
        public DataTable Read(string sql, params object[] obj)
        {
            return Read(string.Format(sql, obj));
        }

        /// <summary>
        /// Прочитать данные
        /// </summary>
        /// <returns></returns>
        public DataTable Read()
        {
            return Read("SELECT * FROM {0}", LocalFile);
        }

        /// <summary>
        /// Закрытие подключения
        /// </summary>
        public void Dispose()
        {
            LocalConnection.Dispose();
        }
    }
}

class WorkDBF
{
   private OdbcConnection Conn = null;
   public DataTable Execute(string Command)
   {
      DataTable dt = null;
      if (Conn != null)
      {
         try
         {
            Conn.Open();
            dt = new DataTable();
            System.Data.Odbc.OdbcCommand oCmd = Conn.CreateCommand();
            oCmd.CommandText = Command;  
            dt.Load(oCmd.ExecuteReader());
            Conn.Close();
         }
         catch (Exception e)
         {
             MessageBox.Show(e.Message); 
         }
      }
      return dt; 
   }
   public DataTable GetAll(string DB_path)
   {
      return Execute("SELECT * FROM " + DB_path);
   }

   public WorkDBF()
   {
      this.Conn = new System.Data.Odbc.OdbcConnection();
      Conn.ConnectionString = @"Driver={Microsoft dBase  Driver (*.dbf)};" +
             "SourceType=DBF;Exclusive=No;" +
             "Collate=Machine;NULL=NO;DELETED=NO;" +
             "BACKGROUNDFETCH=NO;"; 
   }
}

class WorkDBF
{
   private OdbcConnection Conn = null;
   public DataTable Execute(string Command)
   {
      DataTable dt = null;
      if (Conn != null)
      {
         try
         {
            Conn.Open();
            dt = new DataTable();
            System.Data.Odbc.OdbcCommand oCmd = Conn.CreateCommand();
            oCmd.CommandText = Command;  
            dt.Load(oCmd.ExecuteReader());
            Conn.Close();
         }
         catch (Exception e)
         {
             MessageBox.Show(e.Message); 
         }
      }
      return dt; 
   }
   public DataTable GetAll(string DB_path)
   {
      return Execute("SELECT * FROM " + DB_path);
   }

   public WorkDBF()
   {
      this.Conn = new System.Data.Odbc.OdbcConnection();
      Conn.ConnectionString = @"Driver={Microsoft dBase  Driver (*.dbf)};" +
             "SourceType=DBF;Exclusive=No;" +
             "Collate=Machine;NULL=NO;DELETED=NO;" +
             "BACKGROUNDFETCH=NO;"; 
   }
}