You'd have to pass in the instance of the form you are using ot the instance of the control and probably ByRef.
See in this code:
VB Code:
Sub ChangeText()
dim objForm1 as New Form1
objForm1.TextBox1.Text = "222"
End Text
You are creating a whole new form and then changing the textbox in it. You need to work with the form that is already open. Try something like this:
VB Code:
Sub ChangeText(ByRef Sender as Object, e as System.EventArgs)
dim frm as Form1
frm=CType(Sender,Form1)
frm.TextBox1.Text = "222"
End Text
I'm not sure that is correct but it should be something along that line. And when you call it use this:
VB Code:
Function Command1_onclick
dim objmyClass as New myClass
objmyClass.ChangeText(Me,Nothing)
End Function