Encrypt the password with MD5 Hash in C#

I have created a scene where the user must insert your username and password. For obvious reasons, the password must be encrypted and stored in the database. Next, you will see the snippet to encrypt the password with MD5 Hash

using System.Security.Cryptography;

public class Login{
 private MD5 md5 = new MD5CryptoServiceProvider();

 private string GenerateMD5Hash(string password){
  md5.ComputeHash (ASCIIEncoding.ASCII.GetBytes (password));
  byte[] result = md5.Hash;
  StringBuilder stringBuilder = new StringBuilder ();
  for (int i=0; i < result.Length; i++) {
   //change it into 2 hexadecimal digits for each byte
   stringBuilder.Append(result[i].ToString ("x2"));
  return stringBuilder.ToString ();