SQL SERVER class

Hello guys, I have managed to connect to SQL server with a simple connection string, and work with table, but I want to biuld a class for this and understand, how class, namespace and properties work.

Code:

---

Namespace SqlDataProvider
    Public NotInheritable Class SqlDatabase
#Region " Local Property Declarations "
        Dim _connectionString As String
#End Region

#Region " Constructor "
        '''<summary>
        ''' Initializes a new instance of the ADO.SqlDatabase class.
        ''' </summary>
        ''' <param name="connectionString">The connection used to open the SQL Server database.</param>
        Public Sub New(ByVal connectionString As String)
            _connectionString = "Data Source=(local); Initial Catalog=Test ; UId =" & Login.UsernameTextBox.Text & _
                                "; Pwd =" & Login.PasswordTextBox.Text & ";"
        End Sub
#End Region
#Region " Public Properties "
        ''' <summary>
        ''' Gets or sets the string used to open a SQL Server database.
        ''' </summary>
        ''' <returns>The connection string that includes the source database name, and other parameters needed to establish the initial connection.</returns>
        Public Property ConnectionString() As String
            Get
                Return _connectionString
            End Get
            Set(ByVal value As String)
                _connectionString = value
            End Set
        End Property
#End Region

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I have found the above code. I have added a login form in my project, and I want connectionstring to read username.text and passwd.text, from loginform.
So as I can understand, connectionstring reads these strings, and with ConnectionString property returns me if these are right for my database or not.
I can't figure out how can I call Sub New from my class, and connectionstring property. Namespace is needed or should I remove them, and change class name?
I have tried to call sub new
New(), or SqlDataProvider.New with no luck.
What am I doing wrong?