gridview updating database using textboxs

Sorry that was aspx file here is the profile.cs using System; using System.Collections; using System.Configuration; using System.Data; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; using System.Xml.Linq; namespace GYM_APP { public partial class Profile : System.Web.UI.Page { protected void Page_Init(object sender, EventArgs e) { lbl1.Text = Convert.ToString(Session["UserNn"]); } protected void Page_Preload(object sender, EventArgs e) { GridView1.DataBind(); } protected void Page_Load(object sender, EventArgs e) { txtDateTime.Text = GridView1.Rows[0].Cells[0].Text; txtFname.Text = GridView1.Rows[0].Cells[1].Text; txtLname.Text = GridView1.Rows[0].Cells[2].Text; txtIDNumber.Text = GridView1.Rows[0].Cells[3].Text; txtAge.Text = GridView1.Rows[0].Cells[4].Text; txtGender.Text = GridView1.Rows[0].Cells[5].Text; txtAddress.Text = GridView1.Rows[0].Cells[6].Text; txtContact.Text = GridView1.Rows[0].Cells[7].Text; txtEmail.Text = GridView1.Rows[0].Cells[8].Text; txtHobbies.Text = GridView1.Rows[0].Cells[9].Text; txtAbout.Text = GridView1.Rows[0].Cells[10].Text; txtFav.Text = GridView1.Rows[0].Cells[11].Text; txtTrainer.Text = GridView1.Rows[0].Cells[12].Text; txtUsername.Text = GridView1.Rows[0].Cells[13].Text; txtPass.Text = GridView1.Rows[0].Cells[14].Text; txtQ.Text = GridView1.Rows[0].Cells[15].Text; txtA.Text = GridView1.Rows[0].Cells[16].Text; Image1.ImageUrl = GridView1.Rows[0].Cells[17].Text; } protected void btnUpdate_Click(object sender, EventArgs e) { if (FileUpload1.HasFile) { string picture1 = FileUpload1.SaveAs("F:/GYM APP/GYM APP/Profile Pics/" + FileUpload1.FileName + ".jpg"); Msg1.Visible = true; lblPro.Text = "Successfully uploaded picture"; Session["Pic1"] = picture1; } else { Msg1.Visible = true; lblPro.Text = ""; } } protected void LinkLname_Click(object sender, EventArgs e) { txtLname.Enabled = true; } } }