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Don't do it like that! Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Always use Parameterized queries instead.

When you concatenate strings, you cause problems because SQL receives commands like:

SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'

The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:

SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;--'

Which SQL sees as three separate commands:

SELECT * FROM MyTable WHERE StreetAddress = 'x';

A perfectly valid SELECT

DROP TABLE MyTable;

A perfectly valid "delete the table" command

--'

And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.

So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?

And ... in order to read information from the DB, you will need two things:
1) An Open connection to the DB. Don't share connections, create them and open them when you need them. They are scarce resources and it can cause problems later if you try to recycle them. Ideally, a using block around the connection and command is recommended.
2) Creating an SqlCommand does not mean that SQL will execute it! You need to call ExecuteReader, ExecuteScalar, ExecuteReader, or one of the DataAdapter methods to actually interface with the DB system.

using (SqlConnection con = new SqlConnection(strConnect))
    {
    con.Open();
    using (SqlCommand cmd = new SqlCommand("SELECT Id, description FROM myTable where MyName=@Name", con))
        {
        cmd.Parameters.AddWithValue("@Name",tbUserName.Text);
        using (SqlDataReader reader = cmd.ExecuteReader())
            {
            while (reader.Read())
                {
                int id = (int) reader["Id"];
                string desc = (string) reader["description"];
                Console.WriteLine("ID: {0}\n    {1}", id, desc);
                }
            }
        }
    }