How to set delay without freezing/locking GUI

I am working on a program that i already written in Python. But now i'm trying to make same program in c#. Problem isdelay. Thread.sleep() freezes GUI, same thing in python.  But i found solution in python with:   after(seconds, execute). How ever i don't see clear solution in c#, i was reading some stuff from forums but i just can't fit it in my code. This is what i need to delay:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Threading;
namespace Cworm
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void toolTip1_Popup(object sender, PopupEventArgs e)
        {
            
        }

        private void activate_b_Click(object sender, EventArgs e)
        {
            string cstrike;
            cstrike = pathbox.Text;
            if (Directory.Exists(cstrike) && File.Exists(cstrike + @"\config.cfg")) // postoji li cstrike folder & config.cfg
            {
                string config = cstrike + @"\config.cfg";              
                // delay for 3 seconds here <-----------------------
                status.Text = "delayed";
                // delay for 3 seconds here <-----------------------
                backup(config);
            }
            else
                status.Text = "Invalid path";


        }
        private void backup(string config)
        {
            string backup_dir = Directory.GetCurrentDirectory();
            activate_b.Enabled = false;
            stop_b.Enabled = true;
        }

        private void stop_b_Click(object sender, EventArgs e)
        {
            stop_b.Enabled = false;
            activate_b.Enabled = true;
        }

    }
}

Thank you in advance!