VB: Populate a textbox with popup from txt - vb.net

Question

I am creating a vb file, and I have a txt file with some that I want to populate a textbox.
What it is currently doing: It is choosing an option that i input in the textbox that I have created.
What I want it to do: Create a popup with every option from a textbox file, show it on screen, let me choose, and then populate another textbox with my choice.
Current code and screenshot:
Public Class Form1
Private Sub TextBox1_MouseClick(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles TextBox1.MouseClick
Dim f As New Form2
Try
f.Owner = Me
'
' Before showing the child form populate TextBoxes
'
f.TextBox1.Text = "1"
f.TextBox2.Text = "2"
f.TextBox3.Text = "3"
If f.ShowDialog = Windows.Forms.DialogResult.OK Then
Dim Box = (From T In f.Controls.OfType(Of TextBox)()
Where Not String.IsNullOrWhiteSpace(T.Text)
Select T Order By T.Name).FirstOrDefault
If Box IsNot Nothing Then
Me.TextBox1.Text = Box.Text
End If
End If
Finally
f.Dispose()
End Try
End Sub
End Class
Form 2
Public Class Form2
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
Dim Box = (From T In Controls.OfType(Of TextBox)()
Where Not String.IsNullOrWhiteSpace(T.Text)
Select T Order By T.Name).FirstOrDefault
If Box IsNot Nothing Then
CType(Me.Owner, Form1).TextBox1.Text = Box.Text
End If
CType(Me.Owner, Form1).ActiveControl = CType(Me.Owner, Form1).cmdClose
Close()
End Sub
End Class
Image:
edit: now i only need to make the checkbox into locked textboxes, one line from the text file each.