класс

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Text.RegularExpressions;

namespace Converter
{
    class WebManager
    {
        public string ConnectionAndSearch(string _moneyType)
        {
            string Money_course = "";
            string pattern = "";
            System.Net.WebClient wc = new System.Net.WebClient();
            string Response = wc.DownloadString("http://www.finmarket.ru/currency/rates/");
            if(_moneyType.Equals("euro"))
            {
                pattern = @"EUR</div><div class=""value"">(\d*,\d*)";
            }
            else if (_moneyType.Equals("dollar"))
            {
                pattern = @"USD</div><div class=""value"">(\d*,\d*)";
            }
            else if (_moneyType.Equals("funt"))
            {
                pattern = @"GBP</div><div class=""value"">(\d*,\d*)";
            }


            MatchCollection matches = Regex.Matches(Response, pattern);
            if (matches.Count > 0)
            {
                foreach (Match match in matches)
                    Money_course = match.Groups[1].Value;
            }


            return Money_course;
        }

    }
}