here is some sample code in your userform (edit/adapt to suit). Note: it is assumed that the rows in the textbox have newline characters -- i.e., you've entered Control + Enter after each value or something of the sort. This is at best odd and at worst a poor choice for storing data - textboxes are not meant to store many rows of data in a structured manner - though you've certainly got me wondering how you end up with one that does. Can you not put this data on a spreadsheet to begin with?
Private Sub CommandButton1_Click()
Dim a As Variant
a = Split(Me.TextBox1.Value, vbNewLine)
Sheet2.Range("B1").Resize(UBound(a) + 1, 1).Value = Application.Transpose(a)