How do I put text on ProgressBar?

You will have to override the OnPaint method, call the base implementation and the paint your own text.

You will need to create your own CustomProgressBar and then override OnPaint to draw what ever text you want.

Custom Progress Bar Class

namespace ProgressBarSample
{

public enum ProgressBarDisplayText
{
    Percentage,
    CustomText
}

class CustomProgressBar: ProgressBar
{
    //Property to set to decide whether to print a % or Text
    public ProgressBarDisplayText DisplayStyle { get; set; }

    //Property to hold the custom text
    public String CustomText { get; set; }

    public CustomProgressBar()
    {
        // Modify the ControlStyles flags
        //http://msdn.microsoft.com/en-us/library/system.windows.forms.controlstyles.aspx
        SetStyle(ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint | ControlStyles.OptimizedDoubleBuffer, true);
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        Rectangle rect = ClientRectangle;
        Graphics g = e.Graphics;

        ProgressBarRenderer.DrawHorizontalBar(g, rect);
        rect.Inflate(-3, -3);
        if (Value > 0)
        {
            // As we doing this ourselves we need to draw the chunks on the progress bar
            Rectangle clip = new Rectangle(rect.X, rect.Y, (int)Math.Round(((float)Value / Maximum) * rect.Width), rect.Height);
            ProgressBarRenderer.DrawHorizontalChunks(g, clip);
        }

        // Set the Display text (Either a % amount or our custom text
        int percent = (int)(((double)this.Value / (double)this.Maximum) * 100); 
        string text = DisplayStyle == ProgressBarDisplayText.Percentage ? percent.ToString() + '%' : CustomText;            

        using (Font f = new Font(FontFamily.GenericSerif, 10))
        {

            SizeF len = g.MeasureString(text, f);
            // Calculate the location of the text (the middle of progress bar)
            // Point location = new Point(Convert.ToInt32((rect.Width / 2) - (len.Width / 2)), Convert.ToInt32((rect.Height / 2) - (len.Height / 2)));
            Point location = new Point(Convert.ToInt32((Width / 2) - len.Width / 2), Convert.ToInt32((Height / 2) - len.Height / 2)); 
            // The commented-out code will centre the text into the highlighted area only. This will centre the text regardless of the highlighted area.
            // Draw the custom text
            g.DrawString(text, f, Brushes.Red, location);
        }
    }
}
}

Sample WinForms Application

using System;
using System.Linq;
using System.Windows.Forms;
using System.Collections.Generic;

namespace ProgressBarSample
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            // Set our custom Style (% or text)
            customProgressBar1.DisplayStyle = ProgressBarDisplayText.CustomText;
            customProgressBar1.CustomText = "Initialising";
        }

        private void btnReset_Click(object sender, EventArgs e)
        {
            customProgressBar1.Value = 0;
            btnStart.Enabled = true;
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            btnReset.Enabled = false;
            btnStart.Enabled = false;

            for (int i = 0; i < 101; i++)
            {

                customProgressBar1.Value = i;
                // Demo purposes only
                System.Threading.Thread.Sleep(100);

                // Set the custom text at different intervals for demo purposes
                if (i > 30 && i < 50)
                {
                    customProgressBar1.CustomText = "Registering Account";
                }

                if (i > 80)
                {
                    customProgressBar1.CustomText = "Processing almost complete!";
                }

                if (i >= 99)
                {
                    customProgressBar1.CustomText = "Complete";
                }
            }
                        
            btnReset.Enabled = true;


        }

   
    }
}