Help realise download file from Dropbox folder on Visual Basic 2015

Since more than 6 months iam trying to figure it out, but it looks impossible to me, Finally iam here now 

I wanna ask, i have uploaded a text file to dropbox, and i can see its content in my forms in VB.Net here is the code i used

Dim myWebClient As New System.Net.WebClient
Dim file As New System.IO.StreamReader(myWebClient.OpenRead("https://www.dropbox.com/s/yfarlrua18vbajo/PRUEBA.txt?dl=1"))
RichTextBox1.Text = file.ReadToEnd()
file.Close()

Now my Question is how can i edit this text or add more text into my text file from my VB application ? Is there any other way to edit this text from Visual basic only without using dropbox API ?