how to copy file uploads path to Textbox

You can't get the full file path of the client side original file path. but you can get the file name as below

fileNameTxt.Text =fileupload.FileName;

if you need to display the content of the file in a text box;

protected void  btnUpoad_ServerClick(object sender, EventArgs e)
{
    if(fileupload1.HasFile)
    {
        fileNameTxt.Text =fileupload.FileName.ToString();
        fuUpload.SaveAs(Server.MapPath("images")+"\\"+fileupload1.FileName);
        fileContent.Text =File.ReadAllText(Server.MapPath("images")+"\\"+fileupload1.FileName);
    }
}