Q:

Insert String value into Database C#

I've got my passwords to be hashed in my ASP.NET Webforms. 
How do I then enter the hashed password into the database via a string? 
SqlConnection dbCon = new SqlConnection(ConfigurationManager. ConnectionStrings["ConMotorstore"].ConnectionString);

dbCon. Open();

SqlCommand cmd = new SqlCommand("INSERT INTO [user] VALUES (@firstName, @surname, @email, @username, @passwordHash)", dbCon);

cmd. Parameters. AddWithValue("firstName", firstNameTxt. Text);
cmd. Parameters. AddWithValue("surname", surnameTxt. Text);
cmd. Parameters. AddWithValue("email", emailTxt. Text);
cmd. Parameters. AddWithValue("username", usernameTxt. Text);

string passwordHash = BCrypt. Net. BCrypt. HashPassword(passwordTxt. Text);
cmd. Parameters. ToString("passwordHash");

cmd. ExecuteNonQuery();

I knew I couldn't use .AddWithValue and thought of .ToString may have been the one to use. 
I am new to C#. 
Thanks. 

A:

Does this work? 
   SqlConnection dbCon = new SqlConnection(ConfigurationManager. ConnectionStrings["ConMotorstore"].ConnectionString);
{
    dbCon. Open();
    SqlCommand cmd = new SqlCommand("INSERT INTO [user] VALUES (@firstName,@surname,@email,@username,@passwordHash)", dbCon);
    cmd. Parameters. AddWithValue("firstName", firstNameTxt. Text);
    cmd. Parameters. AddWithValue("surname", surnameTxt. Text);
    cmd. Parameters. AddWithValue("email", emailTxt. Text);
    cmd. Parameters. AddWithValue("username", usernameTxt. Text);
    string passwordHash = BCrypt. Net. BCrypt. HashPassword(passwordTxt. Text);
    cmd. Parameters. AddWithValue("passwordHash", passwordHash);

    cmd. ExecuteNonQuery();

