How to grab a part of text from a local HTML file and use it as variable?

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VB

Visual-Studio

I am making a small "home" application using VB. As the title says, I want to grab a part of text from a local html file and use it as variable, or put it in a textbox.

What I have tried:

I have tried something like this...

Private Sub Open_Button_Click(sender As Object, e As EventArgs) Handles Open_Button.Click
    Dim openFileDialog As New OpenFileDialog()
    openFileDialog.CheckFileExists = True
    openFileDialog.CheckPathExists = True
    openFileDialog.FileName = ""
    openFileDialog.Filter = "All|*.*"
    openFileDialog.Multiselect = False
    openFileDialog.Title = "Open"

    If openFileDialog.ShowDialog = Windows.Forms.DialogResult.OK Then
        Dim fileReader As String = My.Computer.FileSystem.ReadAllText(openFileDialog1.FileName)
            TextBox.Text = fileReader
    End If
End Sub

The result is to load the whole html code inside this textbox. What should I do so to grab a specific part of html files's code? Let's say I want to grab the word text from this span...

<span id="text">Text</a>