Getting current Logged In UserId

using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Security.AccessControl;
using System.Web.Security;
using System.Configuration;
using System.Data.SqlClient;
 
public partial class Models_CreateProfile : System.Web.UI.Page
    {
    protected void Page_Load(object sender, EventArgs e)
        {
 
        }
 
        
 
    protected void Button1_Click(object sender, EventArgs e)
        {
        // Get the UserId of the logged in user 
        MembershipUser newUser = Membership.GetUser(User.Identity.Name);
        Guid newUserId = (Guid)newUser.ProviderUserKey;
 
        //Get Profile Data Entered by user in TextBox               
        String FirstName = ((TextBox)FindControl("FirstName")).Text;
        String LastName = ((TextBox)FindControl("LastName")).Text;
 
        // Insert a new record into User_Profile
 
        // Get your Connection String from the web.config
 
        string connectionString = ConfigurationManager.ConnectionStrings["LocalSqlServer"].ConnectionString; string insertSql = "INSERT INTO Profile(UserId,FirstName, LastName) VALUES(@UserId, @FirstName, @LastName)";
 
        using (SqlConnection myConnection = new SqlConnection(connectionString))
            {
 
            myConnection.Open();
            SqlCommand myCommand = new SqlCommand(insertSql, myConnection);
 
            myCommand.Parameters.AddWithValue("@UserId", newUserId);
            myCommand.Parameters.AddWithValue("@FirstName", FirstName);
            myCommand.Parameters.AddWithValue("@LastName", LastName);
            myCommand.ExecuteNonQuery();
            myConnection.Close();
 
            }
        }
}