How to encrypt and decrypt password in c# with sqlserver

Hi Friends,

I have made registraion page. I want to store user's password in database and in encryption form and when user login it should be decrypt. can you please tell me the the code how to encrypt and decrypt password.

I have made two function for that but it give me error like String does not exist in current context. so i can't understand now what to do.

If anyone have full code of encryption and decryption using MD5 or SHA1 then please send me. or please try to solve my error.

The function which i have made that are given below.

 public string Encrypt(string Text)
    {
        int I;
        string encr = "";
        for (I = 1; I <= Text.Length; I++)
        {
           encr ...