Here is the code for the first forms button click event:
Private Sub button1_Click(sender As Object, e As EventArgs)
Dim frm2_1 As New Form2("Hello")
frm2_1.Show()
Dim frm2_2 As New Form2("World")
frm2_2.Show()
End Sub
and for the constructor of the second form you could use something like that:
Namespace WindowsFormsApplication1
Public Partial Class Form2
Inherits Form
Public Sub New(strContent As String)
InitializeComponent()
textBox1.Text = strContent
End Sub
End Class
End Namespace