PostgreSQL connection with C #

then I leave the code I am using to connect and insert records in my database

NpgsqlConnection conn = new NpgsqlConnection("Server=localhost;Port=5432;Database=demoluis;User Id=Luis;Password=micontraseña;");
        conn.Open();
        NpgsqlCommand Command = new NpgsqlCommand("insert into nombres values(" + textBox1.Text + ")",conn);
        Command.ExecuteNonQuery();
        textBox1.Clear();
        conn.Close();

The problem is that at the moment of trying to insert a record in my database my throws the following errors of which I do not understand what can be done

{"28P01: la autentificaci�n password fall� para el usuario �Luis�"}
{"No password has been provided but the backend requires one (in MD5)"}

this happens when I remove and put the password ...

It is worth mentioning that I am using npgsql, Mono.Security with the most stable and recent versions

pd: if you ask me why I only have one table it is because I am only practicing but this error is not how to solve it ...