C# and Trackbar

I am finding it difficult to control the speed of an SVR robot using a trackbar and having the speed displayed on a text box.
I have been able to write athe codes for the directiuonal control of robot, created the trackbar and the value of the track bar displays on the textbox but I don't know how to make this trackbar control the speed of the robot movement. Please some urgent help needed.

here is my code




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;

namespace Mobile_Robot
{
    public partial class Mobile_Robot : Form
    {
        public Mobile_Robot()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Sp.Open();          //connect
        }

        private void button3_Click(object sender, EventArgs e)
        {
            Sp.Write("8");      //go forward
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Sp.Write("5");      //stop
        }

        private void button4_Click(object sender, EventArgs e)
        {
            Sp.Write("2");      //reverse
        }

        private void button5_Click(object sender, EventArgs e)
        {
            Sp.Write("6");      //right
        }

        private void button6_Click(object sender, EventArgs e)
        {
            Sp.Write("4");      //left
        }

        private void button7_Click(object sender, EventArgs e)
        {
            Sp.Close();         //disconnect
        }

        private void button9_Click(object sender, EventArgs e)
        {
            Sp.Write("7");       //drift left
        }

        private void button8_Click(object sender, EventArgs e)
        {
            Sp.Write("9");      //drift right
        }

        private void button11_Click(object sender, EventArgs e)
        {
            Sp.Write(".");      //rotate right by 20 degrees
        }

        private void button10_Click(object sender, EventArgs e)
        {
            Sp.Write("0");      //rotate left by 20 degrees
        }

        private void button12_Click(object sender, EventArgs e)
        {
            Sp.Write("1");      //back left
        }

        private void button13_Click(object sender, EventArgs e)
        {
            Sp.Write("3");      //back right
        }


        private void Slider_Scroll(object sender, EventArgs e)
        {
            Slider.Text = Convert.ToInt16(Slider.Value).ToString();
            //converts the double (Slider.Value) into integer
            //then to a string in other to display in the text box

           
            Slider.Maximum = 10;
            // The Maximum property sets the value of the track bar when
            // the slider is all the way to the right.


            Slider.Minimum = 0;
            // The Minimum property sets the value of the track bar when
            // the slider is all the way to the left.


            Slider.TickFrequency = 2;  
            // The TickFrequency property establishes how many positions
            // are between each tick-mark.


            Slider.LargeChange = 1;
            // The LargeChange property sets how many positions to move
            // if the bar is clicked on either side of the slider.


            Slider.SmallChange = 2;
            // The SmallChange property sets how many positions to move
            // if the keyboard arrows are used to move the slider.
           


            Speed.Text = "" + Slider.Value;      
            // Display the trackbar value in the text box.

        }
    }
}


and here is the GUI